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Zatta, Amanda J., i n/a. "Adenosine and the Coronary Vasculature in Normoxic and Post-Ischaemic Hearts". Griffith University. School of Health Science, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20051130.124230.
Pełny tekst źródłaZatta, Amanda J. "Adenosine and the Coronary Vasculature in Normoxic and Post-Ischaemic Hearts". Thesis, Griffith University, 2004. http://hdl.handle.net/10072/367305.
Pełny tekst źródłaThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Health Sciences
Full Text
Hack, Benjamin Daniel, i n/a. "Characterisation and Application of the Isolated Perfused Murine Heart Model and the Role of Adenosine and Substrate During Ischaemia-Reperfusion". Griffith University. School of Health Science, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060810.144732.
Pełny tekst źródłaHack, Benjamin Daniel. "Characterisation and Application of the Isolated Perfused Murine Heart Model and the Role of Adenosine and Substrate During Ischaemia-Reperfusion". Thesis, Griffith University, 2005. http://hdl.handle.net/10072/365760.
Pełny tekst źródłaThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Health Sciences
Full Text
Edroos, Sadat Ali. "Myocardial ischaemia-reperfusion injury and its reduction by remote ischaemic preconditioning in health and diabetes mellitus". Thesis, University of Leicester, 2014. http://hdl.handle.net/2381/31983.
Pełny tekst źródłaAwad, Wael Ibrahim Issa. "Ischaemic preconditioning in the neonatal rat heart". Thesis, King's College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391636.
Pełny tekst źródłaKato, Rie. "Ischaemic injury in the heart : protective effects of anaesthetic agents". Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343043.
Pełny tekst źródłaZhang, Liqun. "Effect of streptozotocin induced diabetes on the susceptibility of ex vivo rat heart". Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248572.
Pełny tekst źródłaAmrani, Mohamed. "Postischemic coronary flow and reperfusion injury". Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307467.
Pełny tekst źródłaConnaughton, Mark. "Aspects of ischaemia and reperfusion injury in the isolated rat heart". Thesis, King's College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266208.
Pełny tekst źródłaGroves, Peter H. "The influence of exogenous nitric oxide on the pathophysiology of angioplasty injury". Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308763.
Pełny tekst źródłaSee, Hoe Louise. "Mechanisms and Clinical Utility of Sustained Ligand-Activated Preconditioning". Thesis, Griffith University, 2016. http://hdl.handle.net/10072/365566.
Pełny tekst źródłaThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Medical Science
Griffith Health
Full Text
Scarabelli, Tiziano Maria. "Endothelial and myocyte apoptosis in the heart exposed to ischaemia/reperfusion injury". Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408258.
Pełny tekst źródłaChouchani, Edward Thomas. "Mitochondrial protein S-nitrosation in the living heart during ischaemia-reperfusion injury". Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607866.
Pełny tekst źródłaPatel, Vanlata Chhotabhai. "The role of nitric oxide in ischaemia reperfusion injury in the rabbit heart". Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243787.
Pełny tekst źródłaBefroy, Douglas Eugene. "Osmotic shock : modulation of contractile function, pHâ†i and ischaemic damage in the perfused guinea-pig heart". Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326024.
Pełny tekst źródłaTsang, Sharon. "Role of testosterone and its interaction with adrenoceptor in protection against ischaemic insult and contractile function of the heart". Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41290732.
Pełny tekst źródłaAu-Yeung, Ka-wai. "Role of Chinese medicinal compounds in the regulation of stress-activated protein kinase in ischaemic/reperfused rat heart". Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22505441.
Pełny tekst źródłaReidy, Victoria A. "Haemin-induced haemoxygenase (HO-1) expression in ischaemia/reperfusion injury of the rat heart". Thesis, University of Bath, 2003. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275826.
Pełny tekst źródłaHussain, A. "The role of A3 adenosine receptors in protecting the myocardium from ischaemia/reperfusion injury". Thesis, Coventry University, 2009. http://curve.coventry.ac.uk/open/items/678ba5ca-5a6f-dbfc-b915-1d7117f8201c/1.
Pełny tekst źródła歐楊嘉慧 i Ka-wai Au-Yeung. "Role of Chinese medicinal compounds in the regulation of stress-activated protein kinase in ischaemic/reperfused rat heart". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31223916.
Pełny tekst źródłaReichelt, Melissa. "Cardiovascular Injury: The Role of Adenosine and Cytokines". Thesis, Griffith University, 2007. http://hdl.handle.net/10072/365596.
Pełny tekst źródłaThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Medical Science
Faculty of Medical Science
Full Text
Yan, Wing-yi, i 殷詠儀. "The role of Ca2+ in protection of preconditioning and ischaemia-induced injury in the rat heart". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29690420.
Pełny tekst źródłaHartley, Shahiem. "The role of p38 MAPK activation in preconditioning mediated protection against ischaemia/reperfusion injury". Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53163.
Pełny tekst źródłaENGLISH ABSTRACT: The ultimate consequence of the interruption of blood flow to the myocardium is necrosis. In view of the prevalence of coronary artery disease in the general population, and the deleterious effects of myocardial ischaemia on myocardial tissue, it is important to develop new strategies to protect the myocardium against ischaemia. Necrosis of myocardial tissue has for a long time been considered to be the main component of the damage incurred by myocardial infarction. Recently the importance of the contribution of apoptotic cell death in the context of myocardial ischaemia/reperfusion injury has become apparent. There is a general agreement that early reperfusion is necessary to salvage myocardial tissue from cell death. Preconditioning is the phenomenon whereby brief episodes of ischaemia and reperfusion protect the heart against a subsequent longer period of ischaemia. This endogenous mechanism is the strongest form of protection against myocardial infarction that has yet been described. Apart from ischaemie preconditioning (IPC), protection can also be elicited with pharmacologic agents, such as activation of the beta-adrenergic receptor with isoproterenol. Ischaemie preconditioning protects the myocardium against necrosis, arrhythmias and apoptosis, and increases functional recovery upon reperfusion. Betaadrenergic receptor stimulated preconditioning (PPC) has been shown to improve post-ischaemie functional recovery, but it is not known whether it also protects against myocardial infarction and apoptosis. The signaling pathways involved in preconditioning have been extensively studied. A distinction is usually made between factors that act as triggers, or as mediators of protection. Triggers activate cellular responses before the onset of sustained ischaemia, and its involvement is demonstrated by showing that inhibitors of the trigger bracketing the preconditioning protocol can block its protective effect, or that transient administration with washout before sustained ischaemia can activate a protective effect. A mediator operates during sustained ischaemia, and its involvement is demonstrated by showing that infusion of an inhibitor of its action immediately prior to sustained ischaemia (without washout) can block its protective effect. Another approach to demonstrate a mediator role is to attempt to activate signal transduction pathways during sustained ischaemia. As it is not possible to infuse substances during ischaemia, activators are infused immediately prior to ischaemia without washout of the agent and subsequently its effect on protection is observed. It is clear that the evolutionary conserved stress activated pathways are involved in preconditioning. There are three pathways i.e., the extracellular receptor activated pathways (ERK), c-jun terminal activated kinases (JNK) and p38 mitogen-activated protein kinases (MAPK). The precise role of the p38 MAPK pathway has not been elucidated. Experimental evidence has suggested a role for the activation of p38 MAPK as a trigger, as well as a mediator of the protective effect of preconditioning. There is however also strong evidence that the attenuation of p38 MAPK activation during sustained ischaemia, rather than its activation, is responsible for the protection that is observed. Furthermore, the role of p38 MAPK has only been investigated in relation to its protection against necrosis, but not apoptosis. AIMS: The aim of this study was to: (I) Establish a model of preconditioning in neonatal cardiomyocyte cell culture. The reason was that such a model could potentially enable one to rapidly elucidate the signal transduction pathways in an environment without the influence of non-cardiac cells. (II) Investigate whether IPC and ~PC protect against necrosis and apoptosis. (III) Elucidate the role of the stress-activated kinase, p38 MAPK, in preconditioning. METHODS: 1. Neonatal rat cardiomyocyte cell culture model A viability assay with 3-[4,5- Dimethylthaizol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) was first developed using different concentrations - a concentration of 0.25% was found to be optimal to determine viability. Neonatal cardiomyocyte cell cultures were subjected to sustained simulated "ischaemia" by using either 5 mM KCN plus deoxyglucose (DOG) for 5 min or potassium cyanide (KCN) for 45 min. Some cell cultures were preconditioned with either chemical ischaemia (5 mM KCN for 5 min) or isoproterenol (10-7 M) for 5 min and 60 min reoxygenation before being exposed to sustained simulated ischaemia. 2. Isolated adult rat cardiomyocyte model Isolated cardiac myocytes were exposed to 2 hours of hypoxia, which was induced by pelletting the cells by centrifugation, and covering them with a thin layer of mineral oil. Some groups were preconditioned with either hypoxia for 10 min at 37° C or isoproterenol (10-7 M) for 5 min, followed by reoxygenation for 20 minutes. The trypan blue exclusion method and MTT method developed in the neonatal cardiomyocytes were used to assess viability. 3. Isolated perfused rat heart model 3.1 Infarct size was determined in a model of regional ischaemia by using tetrazolium staining and determining the area of necrosis (exclusion of tetrazolium) as a percentage of area at risk. These hearts were subjected to 35 min global ischaemia and 30 min reperfusion. Some groups were preconditioned by three cycles of 5 min global ischaemia or addition of isoproterenol (10-7 M) for 5 min, followed by 5 min reperfusion before the onset of sustained regional ischaemia. 3.2 p38 MAPK activation and markers of apoptosis: p38 MAPK activation was determined using antibodies against dual phosphorylated p38 MAPK (i.e. activated p38 MAPK). Apoptosis was measured by using antibodies against activated caspase-3, and against a fragment of PARP (PARP cleavage). For these experiments isolated rat hearts were exposed to global ischaemia for 25 min followed by 30 min reperfusion. Some groups were preconditioned with three cycles of 5 min global ischaemia. A global ischaemia model was used in order to have sufficient tissue available for the Western blot determinations. This necessitated a shorter period of sustained ischaemia, as the globally ischaemie heart does not recover sufficiently after a longer period of ischaemia such as is necessary in regional ischaemia experiments. 3.3 The role of p38 MAPK in ischaemie preconditioning was investigated by administration of SB 203580 (1IJM),a selective inhibitor of p38 MAPK, either bracketing the preconditioning (i.e. to determine its role as a trigger) or for 10 min immediately prior to sustained ischaemia (i.e. to determine its role as a mediator). The second approach was to use anisomycin, an activator of p38 MAPK, as a trigger (infusion for 10 min followed by wash out) or as a mediator (10 min immediately prior to sustained ischaemia) in the same model as used for determination of p38 MAPK activity. The infusion of anisomycin for 10 min has been shown to elicit activation of p38 MAPK to a similar extent as has been observed with an ischaemie preconditioning protocol. The endpoints used were infarct size and markers of apoptosis. RESULTS: 1. Neonatal rat cardiomyocyte cell culture model It was not possible to establish a model of preconditioning of neonatal cardiomyocytes that was consistently successful. It was therefore decided to abandon the attempts and to use a different cell model. 2. Isolated adult rat cardiomyocyte model Isolated adult cardiomyocytes were preconditioned successfully, but produced too little material to perform simultaneous determinations of cell viability and Western blots (p38 MAPK activation and markers of apoptosis). It was therefore decided to use the isolated perfused adult rat heart. 3. Isolated perfused adult rat heart model 3.1 Both IPC and PPCprotect against infarction and apoptosis: Using two models of preconditioning i.e., IPC and PPC, the protective effects of preconditioning were demonstrated convincingly against infarction (necrosis). IPC and PPC both caused a significant reduction in infarct size (12.2±1.4 and 15.2±2.6%) versus Non-PC hearts (29.6±2.9%) (p < 0.001). Both forms of preconditioning also protected against apoptosis, by significantly reducing the markers of apoptosis, caspase-3 activation and PARP cleavage. The protection afforded by both forms of preconditioning was accompanied by a marked decrease in activation of p38 MAPK upon reperfusion. The relationship between p38 MAPK and the protection that was elicited by preconditioning was then investigated, namely whether p38 MAPK acted as a trigger, or as a mediator of protection. To investigate the role of p38 MAPK as a mediator or a trigger in preconditioning, use was made of (i) a specific inhibitor of p38 MAPK activation i.e., SB 203580 and (ii) a known activator of p38 MAPK i.e., anisomycin. 3.2 p38 MAPK as a trigger of protection: Administration of SB 203580 during the IPC protocol and washed out before sustained ischaemia did not abolish the protective effect of ischaemie preconditioning, and resulted in a small, but significant increase in caspase-3 activation and PARP cleavage. On the other hand, activation of p38 MAPK with anisomycin for 10 min followed by washout also resulted in a significant reduction in necrosis (infarct size 14.9±2.2 versus 29.6±2.9% in Non-PC hearts) (p < 0.001) and both markers of apoptosis. The latter results suggested that p38 MAPK was a trigger of preconditioning. If this was the case, why didn't SB 203580 abolish the protection of IPC? The most likely explanation was that multiple protective mechanisms were activated during a multi-cycle protocol of ischaemic preconditioning, of which activation of p38 MAPK was only one. Inhibition of p38 MAPK with SB 203580 would therefore not be expected to block the activation of those mechanisms that were independent of p38 MAPK, but were still capable of protecting against necrosis or apoptosis. It is very interesting that a small increase in apoptosis was observed when SB 203580 was used in this situation, as it may indicate that the protection against apoptosis was more dependent on the activation of p38 MAPK than the protection against necrosis, as no effect was seen on infarct size. Another explanation could be that infarct size determination was not sensitive enough to detect such small effects. 3.3 p38 MAPK as a mediator of protection: Inhibition of p38 MAPK activation with SB 203580 administered 10 min before sustained ischaemia caused a significant decrease in infarct size compared to Non-PC hearts (12.6±1.9 vs 29.6±2.9%) (p < 0.001) equivalent to that of hearts preconditioned with ischaemia. This was accompanied by a similar pattern of protection against apoptosis, with significantly reduced activation of caspase-3 activation and PARP cleavage. These results strongly supported a role for the attenuation of p38 MAPK activation as a mediator of preconditioning against ischaemia/reperfusion-mediated necrosis and apoptosis. However, the results of the experiments with anisomycin were at first glance not compatible with such a conclusion. The administration of the activator of p38 MAPK, anisomycin, for 10 min immediately prior to sustained ischaemia resulted in significant protection against necrosis (infarct size 16.6±2.4% vs 29.6±2.9% in Non-PC hearts) (p < 0.01) and reduced caspase-3 activation and PARP cleavage indicating less apoptosis. The reason for these findings were probably that this method of administration of anisomycin did in fact not activate p38 MAPK during sustained ischaemia, but actually served as a trigger to protect against ischaemia - similarly as if it had been infused with washout of the drug. Support for this notion was found in the fact that p38 MAPK activation was decreased upon reperfusion. These results suggested that the logistical problem of not being able to infuse a drug into the myocardium during ischaemia could not be overcome by immediate prior infusion, and that the administration of anisomycin in this way had activated downstream effectors of the p38 MAPK signal transduction pathway. An important contender for such an effector would be heat shock protein 27 (HSP27), which has been shown to play an important role in protection against apoptosis, and stabilisation of actin, and thus the cytoskeleton. Another possibility was that anisomycin had activated the JNK stress activated kinases. The elucidation of a role of this signal transduction pathway would necessitate the use of anisomycin in the presence of an agent such as curcumin, an inhibitor of JNK. Final conclusion: The work in this thesis showed that the stress activated kinase, p38 MAPK, was involved in the protective effect of ischaemie preconditioning. The results suggested a role for the activation of p38 MAPK as a trigger of protection, and the attenuation of p38 MAPK as a mediator of protection, which was observed in the reduction of both necrosis (infarct size) and apoptosis as determined with caspase- 3 activation and PARP cleavage.
AFRIKAANSE OPSOMMING: Die afsluiting van bloedvloei na die miokardium gee aanleiding tot nekrose. In die lig van die voorkoms van koronêre bloedvatsiekte onder die algemene populasie, en die nadelige effekte van miokardiale isgemie op miokardiale weefsel, is dit belangrik om nuwe strategieë te ontwikkel wat die miokardium teen isgemie beskerm. Nekrose van miokardiale weefsel word tradisioneel as die belangrikste komponent van die skade aangerig deur miokardiale infarksie beskou. Die belang van apoptotiese seldood in die konteks van miokardiale isgemie/herperfusie (I/R) het onlangs na vore getree. Dit word algeneem aanvaar dat vroeë vroegtydige herperfusie noodsaaklik is om miokardiale weefsel te beskerm teen seldood. Prekondisionering is 'n verskynsel waartydens kort episodes van IIR die hart teen 'n daaropvolgende langer periode van isgemie beskerm. Hierdie endogene meganisme is die kragtigste vorm van beskerming teen miokardiale infarksie tot dusver beskryf. Afgesien van isgemiese prekondisionering (IPC), kan beskerming ook deur farmakologiese middels, soos byvoorbeeld die aktivering van die beta-adrenerge reseptore met isoproterenol, ontlok word. IPC beskerm die miokardium teen nekrose, arritmieë en apoptose, en verhoog funksionele herstel na herperfusie. Daar is reeds aangetoon dat betaadrenerge prekonsionering (~PC) post-isgemiese funksionele herstel verbeter, maar dit is nog onbekend of beskerming ook teen miokardiale infarksie en apoptose verleen word. Die seintransduksie paaie betrokke tydens prekondisionering is reeds in detail bestudeer. Daar word gewoonlik tussen faktore wat optree as snellers, of as mediators van beskerming, onderskei. Snellers aktiveer sellulêre response voor die aanvang van volgehoue isgemie, en hul betrokkenheid word aangetoon deurdat inhibisie van snellers tydens die prekondisionering protokol, beskerming ophef. Snellers se effekete kan ook ontlok word deur hulle tydelike toe te dien en dan net voor volgehoue isgemie weer uit te was. Mediators oefen hulle effek tydens volgehoue isgemie uit, en hulle betrokkenheid word gedemonstreer deurdat toediening van inhibitors net voor volgehoue isgemie (sonder uitwas) hulle beskermende effekte ophef. Mediators se rol kan ook aangetoon word deur te poog om seintransduksie paaie tydens volgehoue isgemie te aktiveer. Aangesien dit ontmoontlik is om middels tydens isgemie te infuseer, word aktiveerders onmiddelik voor die aanvang van isgemie toegedien sonder om hulle uit te was, sodat hulle effekte op beskerming vervolgens bestudeer kan word. Dit is duidelik dat die evolusionêr-behoue stres geaktiveerde paaie tydens prekondisionering betrokke is. Daar is drie paaie nl. die ekstrasellulêre reseptor geaktiveerde pad (ERK), c-jun terminaal geaktiveerde kinases (JNK) en p38 mitogeen geaktiveerde proteïen kinases (MAPK). Die spesifieke rol van die p38 MAPK pad is nog nie ontrafel nie. Eksperimentele bewyse stel 'n rol vir die aktivering van p38 MAPK as 'n sneller, sowel as 'n mediator van die beskermende effek van prekondisionering, voor. Daar is egter ook sterk bewyse dat 'n afname in p38 MAPK aktivering tydens volgehoue isgemie, eerder as sy aktivering, verantwoordelik is vir die waargenome beskermende effek. Verder is die rol van p38 MAPK slegs in die konteks van beskerming teen nekrose, maar nie teen apoptose nie, bestudeer. DOELWITTE: Die doelwit van hierdie studie was: (I) Die vestiging van 'n prekondisionering model in neonatale kardiomiosiet in selkultuur. Hierdie model sou potensieel 'n spoedige ontrafeling van die seintransduksie paaie sonder die invloed van nie-kardiale selle bewerkstellig. (II Om ondersoek in te stelof IPC en PPCteen nekrose en apoptose beskerm. (III) Die ontrafeling van die rol van die stres geaktiveerde kinase, p38 MAPK, tydens prekondisionering. METODES: 1. Neonatale rot kardiomiosiet weefselkultuur model 'n Lewensvatbaarheids essai is ontwikkel deur van verskillende konsentrasies van 3-[4,5-dimetielthiazol-2-yl]-2,5-difeniel-tetrazolium bromied (MTT) gebruik te maak - 'n konsentrasie van 0.25% was optimaalom lewensvatbaarheid te bepaal. Neonatale kardiomiosiet weefselkulture is onderwerp aan volgehoue gesimuleerde "isgemie" deur gebruik te maak van 5 mM KCN plus deoksiglukose (DOG) vir 5 minute of 45 min KCN. Sommige weefselkulture is geprekondisioneer deur middel van chemiese isgemie (5 mM KCN vir 5 min) of van isoproterenol (10-7 M) vir 5 minute en 60 minute reoksigenasie alvorens dit bloot gestel is aan volgehoue gesimuleerde isgemie. 2. Geïsoleerde volwasse rot kardiomiosiet model Geïsoleerde kardiomiosiete is aan twee uur hipoksie blootgestel deur selle in 'n pellet te sentrifugeer en met 'n dun lagie mineraalolie te bedek. Sommige groepe is geprekondisioneer deur middel van 10 minute hipoksie by 37°C, of toediening van isoproterenol (10-7 M) vir 5 minute gevolg deur 20 minute reoksigenasie. Die tripaanblou uitsluitings metode en MTT metode soos ontwikkel in die neonatale kardiomiosiet model is gebruik om lewensvatbaarheid te bepaal. 3. Geïsoleerde geperfuseerde volwasse rot hart model 3.1 Infarkgrootte is bepaal met 'n model van streeks isgemie deur van tetrazolium kleuring gebruik te maak, waarna die area van nekrose (uitsluiting van tetrazolium) as 'n presentasie van die risiko area bepaal is. Hierdie harte was onderwerp aan 35 minute globale isgemie en 30 minute herperfusie. Sommige groepe is geprekondisioneer met 3 siklusse van 5 minute globale isgemie, of die toevoeging van isoproterenol (10-7 M) vir 5 minute, gevolg deur 5 minute herperfusie voor die aanvang van volgehoue streeks isgemie. 3.2 p38 MAPK aktivering en merkers van apoptose: p38 MAPK aktivering is bepaal deur gebruik te maak van anti-liggame teen tweeledige gefosforileerde p38 MAPK (d.w.s. geaktiveerde p38 MAPK). Apoptose is bepaal deur gebruik te maak van anti-liggame teen geaktiveerde kaspase-3, en teen 'n fragment van PARP (PARP kliewing). Tydens hierdie eksperimente is geïsoleerde rotharte bloot gestel aan 25 minute globale isgemie gevolg deur 30 minute herperfusie. Sommige groepe is geprekondisioneer met drie siklusse van 5 minute globale isgemie. Om voldoende weefsel vir Westerse klad tegnieke te verkry, is gebruik gemaak van 'n globale isgemie model. As gevolg hiervan was 'n kort periode van volgehoue isgemie genoodsaak, aangesien die globale isgemiese hart nie voldoende herstel na 'n langer periode van isgemie nie, soos wat benodig word in streeks isgemiese eksperimente. 3.3 Die rol van p38 MAPK tydens IPC is bepaal deur die toediening van 'n 1IJM konsentrasie van SB 203580, 'n selektiewe inhibitor van p38 MAPK, hetsy tydens prekondisionering (d.w.s. om die rol as 'n sneller te bepaal), óf vir 10 minute direk voor die aanvang van volgehoue isgemie (d.w.s. om dus sy rol as mediator te bepaal). Die tweede benadering was om anisomisien, 'n aktiveerder van p38 MAPK, as sneller (toediening vir 10 minute gevolg deur uitwassing) of as mediator (10 minute direk voor aanvang van volgehoue isgemie) in dieselfde model as in die geval van p38 MAPK aktiviteit bepaling, te gebuik. Die toediening van anisomisien vir 10 minute het aangetoon dat dit p38 MAPK aktivering kan ontlok tot dieselfde maate as die IPC protokol. Die eindpunte was infarkgrootte en merkers van apoptose. RESULTATE: 1. Neonatale rot kardiomiosiet weefselkultuur model Dit was nie moontlik om 'n suksesvolle model met konsekwente resultate vir die prekondisionering van neonatale kardiomiosiete te vestig nie. Daar is dus besluit om af te sien van hierdie pogings en eerder 'n alternatiewe selmodel te gebruik. 2. Geïsoleerde volwasse rot kardiomiosiet model Geïsoleerde volwasse kardiomiosiete is suksesvol geprekondisioneer, maar het te min materiaalopgelewer vir die gelyktydige bepaling van sellewensvatbaarheid, p38 MAPK aktivering en merkers vir apoptose. Daar is dus besluit om die geïsoleerde geperfuseerde volwasse rothart te gebruik. 3. Geïsoleerde geperfuseerde volwasse rothart model 3.1 Beide IPC en PPCbeskerm teen infarksie en apoptose: Deur gebruik te maak van twee prekondisionering modelle d.w.s. IPC en PPC, is die beskermende effekte van prekondisionering teen infraksie (nekrose) oortuigend gedemonstreer. Beide IPC en PPC het In betekenisvolle afname in infarkgrootle veroorsaak (12.2 ± 1.4 en 15.2 ± 2.6% respektiewelik), vs Nie-PC harte (29.6 ± 2.9%)(p < 0.001). Beide vorme van prekondisionering het ook teen apoptose beskerm deur die apoptose merkers, kaspase-3 aktivering en PARP kliewing te verlaag. Die beskerming verkry deur beide vorms van prekondisionering is geassosieer met In merkbare afname in die aktivering van p38 MAPK na herperfusie. Die verband tussen p38 MAPK en die beskerming ontlok deur prekondisionering is gevolglik ondersoek, naamlik of p38 MAPK optree as 'n sneller of as 'n mediator van beskerming. Om die rol van p38 MAPK as 'n mediator of sneller tydens prekondisionering te ondersoek is daar gebruik gemaak van (I) 'n spesifieke inhibitor van p38 MAPK aktivering nl. SB 203580 en (II) 'n bekende aktiveerder van p38 MAPK nl. anisomisien. 3.2 p38 MAPK as 'n sneller vir beskerming: Toediening van SB 203580 tydens die IPC protokol en uitwassing daarvan voor die aanvang van volgehoue isgemie het nie die beskermende effek van IPC opgehef nie, en het gelei tot 'n klein maar betekenisvolle verhoging in kaspase-3 aktivering en PARP kliewing. Andersins het die aktivering van p38 MAPK met anisomisien vir 10 minute gevolg deur In uitwas ook tot In betekenisvolle afname in nekrose (infarkgrootte 14.9 ± 2.2 vs 29.6 ± 2.9% in Nie-PC harte) (p < 0.001) in beide merkers van apoptose gelei. Laasgenoemde resultate dui daarop dat p38 MAPK inderdaad 'n mediator van prekondisionering is. Indien dit die geval is, waarom het SB 203580 nie die beskermende effek van IPC opgehef nie? Die mees waarskynlike verklaring is dat veelvuldige beskermingsmeganismes tydens 'n multi-siklus protokol van IPC geaktiveer word, waarvan p38 MAPK aktivering slegs een is. Dit is dus onwaarskynlik dat die inhibisie van p38 MAPK met SB 203580 die aktivering van daardie meganismes onafhanklik van p38 MAPK sal blokkeer en steeds in staat sal wees tot beskerming teen nekrose en apoptose. Dit is interessant dat In klein verhoging in apoptose waargeneem is toe SB 203580 gebruik is onder hierdie toestande, aangesien dit daarop kan dui dat die beskerming teen apoptose meer afhanklik was van die aktivering van p38 MAPK as die beskerming teen nekrose, siende dat geen effek op infarkgrootte waargeneem is nie. 'n Verdere verklaring kan wees dat die bepaling van infarkgrootte nie sensitief genoeg is om sulke klein effekte waar te neem nie. 3.3 p38 MAPK as 'n mediator vir beskerming: Inhibisie van p38 MAPK aktivering deur SB 203580 toediening 10 minute voor volgehoue isgemie het 'n betekenisvolle verlaging in infarkgrootte in vergelyking met Nie-PC harte veroorsaak (12.6 ± 1.9 vs 29.6 ± 2.9%) (p < 0.001) soortgelyk aan dié van harte geprekondisioneer met isgemie. Dit is geassosieer met In soortgelyke patroon van beskerming teen apoptose, met betekenisvolle verlaagde kaspase-3 aktivering en PARP kliewing. Hierdie resultate ondersteun die rol van die afname van p38 MAPK aktivering as 'n mediator van prekondisionering teen I/R-gemedieerde nekrose en apoptose. Die resultate van die anisomisien eksperimente was met die eerste oogopslag nie in oorstemming met hierdie gevolgtrekking nie. Die toedienning van die p38 MAPK aktiveerder, anisomisien, vir 10 minute voor volgehoue isgemie het tot 'n betekenisvolle beskerming teen nekrose aanleiding gegee (infarkgrootte 16.6 ± 2.4 vs 29.6 ± 2.9% in Nie-PC harte) (p < 0.01) en verlaagde kaspase-3 aktivering en PARP kliewing wat dui op verlaagde apoptose. Die rede vir hierdie bevindings is moontlik dat die metode van anisomisien toediening nie p38 MAPK geaktiveer het tydens volgehoue isgemie nie, maar eintlik gedien het as 'n sneller vir beskerming teen isgemie - amper asof dit toegedien sou word sonder om uitgewas te word. Ondersteuning vir hierdie aanname word gevind in die feit dat p38 MAPK aktivering verlaag is na herperfusie. Hierdie resultate stel voor dat die logistiese probleem dat In middel nie tydens isgemie toegedien kan word nie, nie oorkom kan word deur onmiddelike voortydige infusie nie, en dat die toediening van anisomisien op hierdie manier gelei het tot die aktivering van stroom-af effektors van die p38 MAPK seintransduksie pad. 'n Belangrike kandidaat vir so 'n effektor is "heat shock protein 27" (HSP27), wat reeds aangetoon is om 'n belangrike rol in die beskerming teen apoptose en destabilisering, en dus die sitoskelet, te speel. 'n Ander moontlikheid is dat anisomisien die JNK stres geaktiveerde kinases geaktiveer het. Die ontrafeling van die rol van hierdie seintransduksie pad noodsaak die gebruik van anisomisien in die teenwoordigheid van 'n agent soos curcumin, 'n JNK inhibitor. Finale gevolgtrekking: Die werk soos vervat in hierdie tesis toon aan dat die stres geaktiveerde kinase, p38 MAPK, betrokke is in die beskermings effek van isgemiese prekondisionering. Die resultate dui op 'n rol vir die aktivering van p38 MAPK as 'n sneller vir beskerming, en die afname in p38 MAPK as 'n mediator vir beskerming, soos waargeneem in die vermindering van veranderlikes van beide nekrose (infarkgrootte) en apoptose soos bepaal deur kaspase-3 aktivering en PARP kliewing.
Rossouw, Ellen. "The effect of androgenic anabolic steroids on the susceptibility of the rat heart to ischaemia and reperfusion injury". Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53105.
Pełny tekst źródłaENGLISH ABSTRACT: Background: Athletes use androgenic anabolic steroids (AAS) to enhance their physical performance. The abuse of AAS is however associated with a host of side effects including sudden death due to cardiac arrest. The use of AAS leads to myocardial hypertrophy, which possibly makes the heart more prone to ischaemia/reperfusion injury, since it often develops in the absence of proper vasculature development. Chronic AAS use also disrupts myocardial p-adrenoreceptor function and possibly cAMP, signalling in the heart. Drugs increasing cAMP and decreasing cGMP levels in the ischaemic myocardium exacerbate myocardial ischaemia/reperfusion injury. We also know that AAS causes coronary artery disease secondary to the deleterious alteration of lipid profiles by increasing the LOL cholesterol and decreasing the HOLcholesterol levels. AAS treatment may increase systemic TNFa levels by stimulating lymphocyte TNFa secretion that has been implicated in the depression of myocardial function, myocardial hypertrophy and the worsening of ischaemia/reperfsuion injury. Aims: To determine whether chronic AAS treatment in trained and untrained rats influences: 1) heart function and susceptibility to ischaemia/reperfusion injury, 2) myocardial cyclic nucleotide levels (cAMP and cGMP) and 3) myocardial TNFa levels. Material and methods: Male Sprague-Dawley rats (n=100) were divided into 4 groups: sedentary vehicle (placebo) treated group, sedentary AAS treated group, exercise vehicle (placebo) treated group, and exercise AAS treated group. Steroid treated animals received an intramuscular injection of nandrolone laureate (0.375 mg/kg) once a week, for six weeks. Training consisted of swim sessions 6 days a week for 6 weeks. Swim time was incrementally increased up to a maximum of 50 minutes a day. For biometric parameters heart weight and body weight were documented. Hearts were mounted on a l.anqendorff perfusion apparatus and left ventricular developed pressure (LVDP), heart rate (HR) and coronary flow (CF) was monitored. The hearts were subjected to a period of 20 minutes of global ischaemia, followed by 30 minutes of reperfusion. Functional parameters was again monitored and documented. For biochemical analysis, blood was collected for the determination of serum lipid levels and myocardial tissue samples were collected before, during and after ischaemia for the determination of myocardial TNFa, cGMP and cAMP levels and p38 activity. Conclusions: Results obtained would suggest that AAS exacerbate exercise induced myocardial hypertrophy. It also prevents the exercise-induced improvement in cardiac function. AAS use reduces reperfusion function in treated hearts, which may suggest that AAS exacerbates ischaemie and reperfusion injury. Furthermore it was seen that AAS elevates basal (preischaemie) cyclic nucleotide levels and basal (pre-ischaemic) as well as reperfusion TNFa levels. This may also contribute to the exacerbation of ischaemic and reperfusion injury.
AFRIKAANSE OPSOMMING: Agtergrond: Androgeniese anaboliese steroïede (AAS) word dikwels deur atlete gebruik om sportprestasie te verbeter. Die misbruik van AAS het egter talle newe effekte, insluitende skielike dood wat gewoonlik toegeskryf word aan hartaanvalle. Die gebruik van AAS lei onder andere tot miokardiale hipertrofie wat opsigself, as gevolg van ontoereikende vaskulêre ontwikkeling tydens die ontwikkeling van hipertrofie, die hart nog meer vatbaar vir isgemie/herperfusie skade maak. Kroniese AAS toediening versteur miokardiale beta-adtenoresepter funksie en moontlik die tweede boodskapper, sAMP, seintransduksie in die hart. Ons weet ook dat AAS koronêre hartvatsiektes veroorsaak. Laasgenoemde is sekondêr tot die nadelige lipiedprofiel verandering, wat 'n verhoging in LDL-C en 'n verlaging in HDL-C insluit. Middels wat miokardiale sAMP vlakke verhoog en sGMP vlakke in die isgemiese miokardium verlaag, vererger miokardiale isgemie/herperfusie skade. AAS behandeling kan moontlik ook sistemiese TNFa vlakke verhoog deur limfosiet TNFa sekresie te stimuleer. Die verhoogde TNFa vlakke word verbind aan die onderdrukking van miokardiale funksie, miokardiale hipertrofie en die verergering van isgemie/herperfusie skade. Doelwitte: Die doelwitte van die studie was om te bepaal of kroniese AAS toediening in geoefende en ongeoefende rotte 1) hartfunksie en die hart se vatbaarheid vir isgemie/herperfusie skade beïnvloed, 2) miokardiale sikliese nukleotiedvlakke (sAMP en sGMP) beïnvloed en 3) miokardiale TNFa-vlakke beïnvloed. Materiale en metodes: Manlike Sprague-Dawley rotte (n=100) is gebruik en in 4 groepe verdeel: 'n ongeoefende placebo groep (kontrole); 'n ongeoefende steroïedbehandelde groep; 'n geoefende placebo groep (kontrole) en 'n geoefende steroïedbehandelde groep. Steroïed behandelde diere het 'n intramuskulêre nandroloon lauraat inspuiting (0.375 mg/kg) een keer per week vir ses weke ontvang. Die oefenprogram het bestaan uit ses swemsessies 'n week vir ses weke. Die swemtyd is geleidelik weekliks verhoog tot by 'n maksimum tyd 50 min. Die waterbadtemperatuur is tussen 30 - 32 oe gehandhaaf. Vir biometriese parameters is hartgewig en liggaamsgewig genoteer. Harte is op 'n Langendorff perfusie apparaat gemonteer en linker ventrikulêre ontwikkelde druk (LVOD), koronêre vloei (KV) en harttempo (HT) is genoteer. Die harte is vervolgens blootgestel aan 20 minute van globale isgemie gevolg deur 'n 30 minute herperfusieperiode. LVOD, KV en HT is weer eens noteer. Vir biochemiese doeleindes is bloed voor perfusie versamelom serum lipied vlakke te bepaal. Miokardiale weefsel is versamel voor, tydens en na isgemie vir die bepaling van TNFa, cGMP en AMP vlakke asook p38 aktiwiteit. Gevolgtrekkings: Na aanleiding van resultate verkry wil dit voorkom asof die gebruik van steroïde oefeningsgeïnduseerde miokardiale hipertrofie vererger. Dit verhoed ook oefeningsgeïnduseerde verbetering in miokardiale funksie. AAS lei tot 'n verlaagde herperfusiefunksie in behandelde harte, wat dalk mag dui op MS verergering van isgemie en herperfusie skade. Verder was daar ook waargeneem dat MS basale (pre-isgemiese) sikliese nukleotiedvlakke en basale TNFa-vlakke sowel as herperfusie TNFa vlakke verhoog. Die verhoging in TNF-a vlakke mag dus moontlik ook bydra tot die verergering van isgemie- en herperfusieskade.
Van, Vuuren Derick. "The role of Protein Phosphatase 2A (PP2A) in myocardial ischaemia/reperfusion injury". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86397.
Pełny tekst źródłaENGLISH ABSTRACT: Ischaemic heart disease is a major contributor to global morbidity and mortality rates. Manoeuvres such as ischaemic preconditioning confer cardioprotection against ischaemia/reperfusion (I/R) injury by activating several intracellular signalling pathways. These pathways have been defined solely in terms of the kinases involved, despite the realization in recent years that protein phosphatase activity also contributes significantly to the attributes of the propagated signal. Protein phosphatase 2A (PP2A) is a heteromultimeric enzyme involved in an array of phosphatase reactions. We hypothesized that PP2A is an important participant in the myocardial response to I/R by regulating intracellular signalling. This project aimed to (i) characterize PP2A during myocardial I/R; (ii) determine the importance of its contribution to the cellular response to I/R; and (iii) investigate its role in the signalling pathways mediated by PKB/Akt, GSK-3β, ERK p42/p44 and p38 MAPK. Two models were used to characterize PP2A during I/R: (i) H9c2 cells exposed to simulated ischaemia (SI) buffer in conjunction with hypoxia (0.5% O2) for a maximum of 2 hours, followed by reoxygenation in standard growth medium for up to 30 minutes; and (ii) isolated working rat hearts exposed to a maximum of 20 minutes global ischaemia and 10 minutes reperfusion. In both models samples were collected at several time points during I/R for Western blotting analysis. PP2A-C (the catalytic subunit) accumulated in the nucleus during early ischaemia, but later redistributed to the cytosol. At the end of ischaemia there was an elevation of PP2A-C relative to PP2A-A in the unfractionated whole cell preparation concomitant with an increase in the inhibitory phosphorylation of PP2A-C. The impact of PP2A activity was evaluated by either inhibiting PP2A using okadaic acid (OA, 10 nM) or activating it by administering FTY720 (1 μM) in an isolated working rat heart model exposed to either 35 minutes of regional ischaemia (RI) with infarct size (IFS) as primary end-point, or 20 minutes global ischaemia (GI) with functional recovery as end-point. The results showed that the pre-ischaemic administration of OA or FTY720 reduced or exacerbated IFS respectively, indicating that PP2A activation during I/R favours cell death. OA and FTY720 were also employed to assess the contribution of PP2A to intracellular signalling in an isolated working rat heart exposed to I/R. Samples were collected at several timepoints and analyzed using Western Blotting. Pre-ischaemic administration of OA enhanced the phosphorylation of PKB/Akt, ERK p42/p44 and GSK-3β at the onset of reperfusion, while FTY720 given before ischaemia reduced the phosphorylation of GSK-3β, p38 MAPK and PKB/Akt at the end of ischaemia and onset of reperfusion. In summary, PP2A is part of an early nuclear-based response to ischaemia, while long-term ischaemia induces an increase in PP2A-C. A portion of this PP2A-C is stored in an inactive form, while an active portion acts as a regulator of the pro-survival signalling components PKB/Akt, GSK- 3β and ERK p42/p44 at the end of ischaemia and the onset of reperfusion. PP2A is therefore an important component of the myocardial response to I/R by regulating pro-survival signalling.
AFRIKAANSE OPSOMMING: Iskemiese hartsiekte is een van die belangrikste komponente wat bydra tot globale morbiditeit en mortaliteit. Ingrepe soos iskemiese prekondisionering aktiveer veelvoudige intrasellulêre seintransduksiepaaie om kardiobeskerming teen iskemie/herperfusie (I/H)-besering te ontlok. Die kinases betrokke in hierdie seintransduksiepaaie is reeds deeglik nagevors, terwyl die potensiële belang van die proteïenfosfatases in seintransduksie tot onlangs misken is. Ons hipotese was dat Proteïenfosfatase 2A (PP2A), wat in ‘n wye verskeidenheid fosfatase reaksies betrokke is, ‘n belangrike rolspeler in die miokardiale reaksie op I/H-besering is, deur deelname aan die regulering van intrasellulêre seintransduksie. Hierdie projek het ten doel gehad om (i) PP2A te karakteriseer tydens miokardiale I/H; (ii) die belang van PP2A in die sellulêre reaksie op I/H-besering te bepaal; en (iii) PP2A se rol in die seintransduksiepaaie, gemedieer deur PKB/Akt, GSK-3β, ERK p42/p44 en p38 MAPK, te evalueer. Twee modelle is aangewend om PP2A tydens I/H te karakteriseer: (i) H9c2-selle blootgestel aan ‘n simuleerde iskemiebuffer tesame met hipoksie (0.5% O2) vir ‘n maksimum van 2 uur gevolg deur heroksiginasie in standaardgroeimedium vir verskillende tydsperiodes tot ‘n maksimum van 30 minute; en (ii) geïsoleerde, werkende rotharte blootgestel aan ‘n maksimum van 20 minute globale iskemie en 10 minute herperfusie. In beide modelle is monsters op verskillende tye versamel vir Western-kladanalise. Tydens vroeë iskemie het PP2A-C in die kern toegeneem, waarna dit met verloop van tyd na die sitosol herversprei het. Teen die einde van iskemie was daar ‘n toename in die vlakke van PP2A-C relatief tot PP2A-A in ongefraksioneerde weefselhomogenate, tesame met ‘n toename in die inhibitoriese fosforilering van PP2A-C. Die belang van PP2A-aktiwiteit is ondersoek deur die effek te bepaal van die inhibisie of aktivering daarvan op infarktgrootte (IFS) en funksionele herstel in ‘n geïsoleerde werkende rothartmodel, blootgestel aan onderskeidelik 35 minute streeksiskemie (RI) of 20 minute globale iskemie. Preiskemiese toediening van die PP2A-inhibitor okadaïensuur (OA, 10 nM), of aktiveerder FTY720 (1 μm) het infarktgrootte respektiewelik beperk of vergroot. PP2A-aktivering tydens I/H is dus nadelig. OA en FTY720 is ook aangewend om die bydrae van PP2A tot I/H-verwante, intrasellulêre seintransduksie in die geïsoleerde, werkende rothart te bepaal. Monsters is op verskeie tydintervalle versamel en ontleed deur gebruik te maak van die Western-kladtegniek. Preiskemiese toediening van OA het die fosforilering van PKB/Akt, ERK p42/p44 en GSK-3β by die aanvang van herperfusie bevoordeel, terwyl pre-iskemiese toediening van FTY720, die fosforilering van GSK-3β, p38 MAPK en PKB/Akt aan die einde van iskemie en die begin van herperfusie verminder het. Ter opsomming: PP2A is deel van ‘n vroeë gelokaliseerde kerngebaseerde reaksie op iskemie, terwyl langdurige iskemie ‘n toename in PP2A-C relatief tot PP2A-A induseer. ‘n Deel van hierdie PP2A-C is onaktief, terwyl die res funksioneer in die regulering van die seintransduksiekomponente PKB/Akt, GSK-3β en ERK p42/p44 wat oorlewing fasiliteer met die aanvang van herperfusie. PP2A is dus ‘n belangrike komponent in die miokardiale reaksie op I/H deurdat dit tot die beheer van seintransduksiepaaie bydra.
Engelbrecht, Anna-Mart. "Investigation into the intracellular mechanisms whereby long-chain fatty acids protect the heart in ischaemia/reperfusion". Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50378.
Pełny tekst źródłaENGLISH ABSTRACT: Although there is evidence for a protective role of long-chain polyunsaturated fatty acids (PUFAs) in cardiovascular disease, their mechanism of action as well as their participation in intracellular signalling processes remain to be elucidated. Therefore the aims of this study were twofold: (i) to characterize the roles of the mitogen-activated protein kinases (MAPKs) and protein kinase B (PKB/Akt) in ischaemia/reperfusion-induced apoptosis of neonatal cardiomyocytes and (ii) to establish whether long-chain PUFAs protect the heart via manipulation of these kinases. Rat neonatal ventricular myocytes exposed to simulated ischaemia and reperfusion (Sl/R) were used to characterize the role(s) of extracellular signalregulated kinase (ERK), p38 and c-Jun NH2-terminal protein kinase (JNK), as well as PKB/Akt in apoptosis. The effects of an omega-3 fatty acid (eicosapentaenoic acid - EPA) and an omega-6 fatty acid (arachidonic acid - ARA) on the response of neonatal rat cardiomyocytes to Sl/R with regard to the above parameters were determined. Exposure of the myocytes to SI (energy depletion induced by KCN and 2- deoxy-D-glucose) reduced cell viability, as measured by the 3-[4,5- dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, and stimulated apoptosis (increased caspase-3 activation and poly(ADP-ribose) polymerase (PARP) cleavage). However, morphological evidence of increased apoptosis (Hoechst 33342 staining) occurred only after reperfusion. A rapid activation of p38 and PKB/Akt Ser473 occurred during SI, while significant activation of ERK and JNK was observed during reperfusion only. Myocytes pre-treated with SB203580, a p38-inhibitor, displayed a significant increase in cell viability and attenuation of apoptosis during Sl/R, while SP600125, a specific JNK inhibitor, significantly increased both caspase-3 activation and the apoptotic index. However, PD98059, an ERK inhibitor, was without effect. Wortmannin, a PI3-kinase inhibitor, reduced PKB/Akt Thr308 but not Ser473 phosphorylation during Sl/R and caused a significant increase in Although there is evidence for a protective role of long-chain polyunsaturated fatty acids (PUFAs) in cardiovascular disease, their mechanism of action as well as their participation in intracellular signalling processes remain to be elucidated. Therefore the aims of this study were twofold: (i) to characterize the roles of the mitogen-activated protein kinases (MAPKs) and protein kinase B (PKB/Akt) in ischaemia/reperfusion-induced apoptosis of neonatal cardiomyocytes and (ii) to establish whether long-chain PUFAs protect the heart via manipulation of these kinases. Rat neonatal ventricular myocytes exposed to simulated ischaemia and reperfusion (Sl/R) were used to characterize the role(s) of extracellular signalregulated kinase (ERK), p38 and c-Jun NH2-terminal protein kinase (JNK), as well as PKB/Akt in apoptosis. The effects of an omega-3 fatty acid (eicosapentaenoic acid - EPA) and an omega-6 fatty acid (arachidonic acid - ARA) on the response of neonatal rat cardiomyocytes to Sl/R with regard to the above parameters were determined. Exposure of the myocytes to SI (energy depletion induced by KCN and 2- deoxy-D-glucose) reduced cell viability, as measured by the 3-[4,5- dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, and stimulated apoptosis (increased caspase-3 activation and poly(ADP-ribose) polymerase (PARP) cleavage). However, morphological evidence of increased apoptosis (Hoechst 33342 staining) occurred only after reperfusion. A rapid activation of p38 and PKB/Akt Ser473 occurred during SI, while significant activation of ERK and JNK was observed during reperfusion only. Myocytes pre-treated with SB203580, a p38-inhibitor, displayed a significant increase in cell viability and attenuation of apoptosis during Sl/R, while SP600125, a specific JNK inhibitor, significantly increased both caspase-3 activation and the apoptotic index. However, PD98059, an ERK inhibitor, was without effect. Wortmannin, a PI3-kinase inhibitor, reduced PKB/Akt Thr308 but not Ser473 phosphorylation during Sl/R and caused a significant increase in Although there is evidence for a protective role of long-chain polyunsaturated fatty acids (PUFAs) in cardiovascular disease, their mechanism of action as well as their participation in intracellular signalling processes remain to be elucidated. Therefore the aims of this study were twofold: (i) to characterize the roles of the mitogen-activated protein kinases (MAPKs) and protein kinase B (PKB/Akt) in ischaemia/reperfusion-induced apoptosis of neonatal cardiomyocytes and (ii) to establish whether long-chain PUFAs protect the heart via manipulation of these kinases. Rat neonatal ventricular myocytes exposed to simulated ischaemia and reperfusion (Sl/R) were used to characterize the role(s) of extracellular signalregulated kinase (ERK), p38 and c-Jun NH2-terminal protein kinase (JNK), as well as PKB/Akt in apoptosis. The effects of an omega-3 fatty acid (eicosapentaenoic acid - EPA) and an omega-6 fatty acid (arachidonic acid - ARA) on the response of neonatal rat cardiomyocytes to Sl/R with regard to the above parameters were determined. Exposure of the myocytes to SI (energy depletion induced by KCN and 2- deoxy-D-glucose) reduced cell viability, as measured by the 3-[4,5- dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, and stimulated apoptosis (increased caspase-3 activation and poly(ADP-ribose) polymerase (PARP) cleavage). However, morphological evidence of increased apoptosis (Hoechst 33342 staining) occurred only after reperfusion. A rapid activation of p38 and PKB/Akt Ser473 occurred during SI, while significant activation of ERK and JNK was observed during reperfusion only. Myocytes pre-treated with SB203580, a p38-inhibitor, displayed a significant increase in cell viability and attenuation of apoptosis during Sl/R, while SP600125, a specific JNK inhibitor, significantly increased both caspase-3 activation and the apoptotic index. However, PD98059, an ERK inhibitor, was without effect. Wortmannin, a PI3-kinase inhibitor, reduced PKB/Akt Thr308 but not Ser473 phosphorylation during Sl/R and caused a significant increase in PARP cleavage during reperfusion, but had no effect on caspase-3 activation or the apoptotic index. EPA and ARA (20 jiM, present before and after SI) significantly reduced caspase-3 activation, PARP-cleavage and the apoptotic index during reperfusion. This was associated with increased ERK- and decreased p38 phosphorylation. Vanadate (a tyrosine phosphatase inhibitor), but not okadaic acid (a serine-threonine phosphatase inhibitor), significantly reduced ARAinduced inhibition of p38 phosphorylation, suggesting involvement of tyrosine phosphatases during Sl/R. MKP-1, a dual-specificity phosphatase, was targeted and a significant induction of MKP-1 by ARA and EPA was observed. An in vitro dephosphorylation assay confirmed that this phosphatase might be responsible for the inhibition of p38 activation. It was also demonstrated that the protective actions of ARA are PI3-K dependent. The results suggest that p38 has a pro-apoptotic role while JNK phosphorylation is protective and that these kinases act via caspase-3 to prevent or promote cell survival in response to SI/R-induced injury. It was demonstrated for the first time that EPA and ARA protect neonatal cardiac myocytes from ischaemia/reperfusion-induced apoptosis through induction of a dual-specific phosphatase, MKP-1, causing dephosphorylation of the proapoptotic kinase, p38. These beneficial effects of ARA and EPA were also reflected by improvement in functional recovery during ischaemia/reperfusion of the isolated perfused rat heart model.
AFRIKAANSE OPSOMMING: Dit word algemeen aanvaar dat lang-ketting poli-onversadigde vetsure teen kardiovaskulere siektes beskerm, maar hul meganisme van aksie sowel as hul invloed op intrasellulere seinoordragpaaie is egter onbekend. Die doelwitte van hierdie studie is dus tweevoudig: (i) om die belang van mitogeen-geaktiveerde proteien kinases (MAPKs) en protein kinase B (PKB/Akt) in isgemie/herperfusie-geinduseerde apoptose vas te stel en (ii) om te bepaal of lang-ketting poli-onversadigde vetsure die hart, deur manipulering van hierdie kinases, beskerm. Rot neonatale ventrikulere miosiete, blootgestel aan gesimuleerde isgemie en herperfusie (Sl/H), is gebruik om die aktivering van ekstrasellulere seingereguleerde kinase (ERK), p38, c-Jun NH2-terminale protein kinase (JNK) asook PKB/Akt tydens apoptose, te karakteriseer. Die effek van ‘n omega-3 vetsuur (eikosapentaenoSsuur - EPA) en ‘n omega-6 vetsuur (aragidoonsuur - ARA) op die respons van bogenoemde kinases in neonatale kardiomiosiete tydens Sl/H, is ondersoek. Blootstelling van miosiete aan SI (energie-uitputting gemduseer deur kaliumsianied en 2-deoksi-D-glukose) het ‘n afname in die vermoe van die sel om te oorleef, soos gemeet deur die MTT (3-[4,5-dimetieltiazol-2-yl]-2,5- difeniel tetrazolium bromied) bepaling, tot gevolg gehad. ‘n Toename in apoptose (kaspase-3 aktivering en poli(ADP-ribose) polimerase (PARP) kliewing) is ook waargeneem. Morfologiese bewyse van apoptose (Hoechst 33342 kleuring) was egter eers tydens herperfusie sigbaar. SI is gekenmerk deur vinnige aktivering van p38 en PKB/Akt Ser473, terwyl ERK en JNK fosforilering slegs tydens herperfusie waargeneem is. Vooraf-behandeling met SB203580, ‘n p38 inhibitor, het ‘n beduidende toename in sellewensvatbaarheid asook ‘n afname in die apoptotiese indeks tydens Sl/H teweeggebring, terwyl SP600125, ‘n spesifieke JNK inhibitor, apoptose bevorder het. PD98059, ‘n ERK inhibitor, het geen invloed op apoptose tydens Sl/H gehad nie. Wortmannin, ‘n PI3-kinase inhibitor, het Thr308 (nie Ser473) fosforilering onderdruk, gepaargaande met ‘n toename in PARP kliewing, maar dit het geen invloed op kaspase-3 aktivering of die apoptotiese indeks gehad nie. EPA en ARA (20 (iM, teenwoordig voor en na SI) het kaspase-3 aktivering en PARP kliewing asook die apoptotiese indeks tydens herperfusie beduidend verminder. Beide vetsure het ook ‘n beduidende toename in ERK en afname in p38 fosforilering veroorsaak. Vanadaat (‘n serien-threonien fosfatase inhibitor), maar nie “okadaic” suur (‘n tirosien fosfatase inhibitor), kon die ARA-gemduseerde inhibisie van p38 ophef nie. Induksie van MKP-1, ‘n tweeledige-spesifieke fosfatase, is beduidend deur ARA en EPA tydens herperfusie verhoog. 'n In vitro defosforileringbepaling het bevestig dat hierdie fosfatase wel betrokke by die inhibisie van p38 kan wees. Daarbenewens is gevind dat die beskermende aksie van ARA PI3-K afhanklik is. Hierdie resultate wys dat fosforilering van p38 pro-apoptoties is, terwyl JNK beskermend is en dat hierdie kinases via kaspase-3 seldood of oorlewing tydens SI/H-geinduseerde beskadiging bemiddel. In hierdie model is daar vir die eerste keer getoon dat EPA en ARA neonatale kardiale miosiete teen isgemie/herperfusie-geinduseerde apoptose beskerm deur induksie van MKP- 1, wat defosforilering van die pro-apoptotiese kinase, p38 teweegbring. Hierdie voordelige effekte van EPA en ARA is ook sigbaar in die funksionele herstel tydens isgemie/herperfusie van die geisoleerde rothart model.
Cross, Heather. "The metabolic and ionic changes occurring during myocardial ischaemia : their interdependence and their roles in contracture and injury". Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308548.
Pełny tekst źródłaEsterhuyse, Adriaan Johannes. "Dietary red palm oil-supplementation offers cardioprotection against Ischaemia/Reperfusion injury : possible cellular mechanisms involved". Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/16514.
Pełny tekst źródłaENGLISH ABSTRACT: Activation of the NO-cGMP pathway is associated with myocardial protection against ischaemia/reperfusion injury. However, high-cholesterol diets alter function of this pathway and these alterations have been implicated in both ischaemic/reperfusion injury and the development of ischaemic heart disease. Little is known about the effects of supplements such as Red Palm Oil (RPO) on the myocardial NO-cGMP-signalling pathway. RPO consists of saturated, mono-unsaturated and poly-unsaturated fatty acids and is rich in antioxidants such as β-carotene and Vitamin E (tocopherols and tocotrienols). The aims of this study were: 1) to determine whether dietary RPO-supplemention protects against ischaemia/reperfusion injury in rats fed a standard rat chow (control) and cholesterol-enriched diets and 2) if so, to investigate possible mechanisms for this protection. Male Long-Evans rats were fed a standard rat chow or a standard rat chow plus cholesterol and/or RPO-supplementation for 6 weeks. Myocardial functional recovery was measured and hearts were freeze-clamped for determination of myocardial phospholipid, cAMP/cGMP concentrations, total myocardial nitric oxide concentrations, lipid hydroperoxide production and superoxide dismutase- and nitric oxide synthase activity in isolated rat hearts subjected to 25 minutes of normothermic total global ischaemia. In addition, the degree of phosphorylation of extracellular signal-regulated kinase (ERK), p38, c-Jun N-terminal protein kinase (JNK) and protein kinase B (PKB/Akt) was investigated. Furthermore, the effect of RPO-supplementation on caspase-3 activation and poly (ADP-ribose) polymerase (PARP)-cleavage in hearts subjected to ischaemia and reperfusion was also investigated. Our data show that dietary RPO-supplementation protects the hearts of rats on a standard rat chow (control) and hypercholesterolaemic diet against ischaemia/reperfusion injury as reflected by improved aortic output recovery. Increased intracellular cardiomyocyte NO concentrations as observed in control hearts supplemented with RPO after 120 minutes hypoxia may contribute to the elevated cGMP concentration and may confer some of the cardioprotection to the ischaemic/reperfused heart. Although improved functional recovery with RPO-supplementation of a high-cholesterol diet was also associated with an increase in intracellular cardiomyocyte NO production after hypoxia compared to the non-hypoxic conditions, it could not be linked to increased NO-cGMP signalling. These data are in agreement with other studies, which showed that high-cholesterol diet impairs NO-cGMP signalling and confirms our hypothesis that elevated cGMP concentrations may not be the only mechanism of protection. We have also shown that RPOsupplementation caused increased phosphorylation of p38 and PKB, reduced phosphorylation of JNK and attenuation of PARP cleavage, which may contribute to the protection of the cell against apoptosis. Based on our results we propose that the myocardial protection offered by RPO-supplementation of rats on a normal and hypercholesterolaemic diet may be associated with either its antioxidant characteristics and/or changes in the fatty acid composition of the myocardium during ischaemia/reperfusion. Furthermore, we demonstrated for the first time that RPO-supplementation protects the isolated perfused working rat heart during reperfusion from ischaemia/reperfusion-induced injury through a MAPK-dependent pathway.
AFRIKAANSE OPSOMMING: Aktivering van die NO-cGMP sein transduksie pad word geassosieer met miokardiale beskerming teen isgemie/herperfusie skade. Hoë cholesterol diëte verander egter die funksie van die pad en hierdie veranderings speel ‘n rol in beide isgemie/herperfusie besering en die ontwikkeling van isgemiese hartsiekte. Daar is egter min inligting beskikbaar oor die uitwerking van aanvullings soos rooi palm olie (RPO) op die miokardiale NO-cGMP sein transduksie pad. RPO bevat versadigde, mono-onversadigde en poli-onversadigde vetsure en is ryk aan anti-oksidante nl. β-karotene en vitamien E (tokoferole en tokotriënole). Die doelwitte van hierdie studie was: 1) om vas te stel of ‘n RPO-aanvulling beskerming bied teen isgemie/herperfusie besering in rotte wat gevoed is met ‘n standaard rotmengsel (kontrole) en cholesterol-verrykte dieet en 2) indien wel, om moontlike meganismes van beskerming te ondersoek. Long-Evans manlike rotte is vir 6 weke gevoer met ‘n standaard rotmengsel of ‘n standaard rotmengsel plus cholesterol en/of RPO-aanvulling. Miokardiale funksionele herstel is gemeet en harte is gevriesklamp vir die bepaling van miokardiale fosfolipied, cAMP/cGMP, totale stikstofoksied, lipied hidroperoksied, superoksied dismutase en stikstofoksied sintase in geïsoleerde rotharte wat vir 25 minute onderwerp was aan normotermiese totale globale isgemie. Hiermee saam is die graad van fosforilering van ekstrasellulêre sein gereguleerde kinase (ERK), p38 mitogeen-geaktiveerde proteïen kinase (p38 MAPK), c-Jun-N-terminale proteïenkinase (JNK) en proteïen kinase B (PKB/Akt) ondersoek, asook kaspase-3 aktivering en poli (ADP-ribose) polimerase (PARP) kliewing in harte blootgestel aan isgemie en herperfusie. Ons resultate toon dat RPO-aanvulling van rotte op ‘n normale en hipercholesterolemiese dieet die hart beskerm soos getoon deur verbeterde herstel van aortiese uitset. Verhoogde intrasellulêre miokardiale NO vlakke in kontrole harte met ‘n RPO-aanvulling wat blootgestel was aan 120 minute hipoksie, mag bygedra het tot die verhoogde cGMP vlakke en beskerming van die hart tydens isgemie en herperfusie. Alhoewel verbeterde funksionele herstel met RPO-aanvulling van ‘n hoë cholesterol dieet ook geassosieer is met ‘n toename in intrasellulêre miokardiale NO produksie ná hipoksiese toestande, kon dit nie verbind word met verhoogde aktivering van die NOcGMP sein transduksie pad nie. Hierdie resultate stem ooreen met ander studies wat aangetoon het dat hoë-cholesterol diëte die NO-cGMP seinpad onderdruk. Hierdie bevinding bevestig ons hipotese dat verhoogde cGMP vlakke moontlik nie die enigste beskermingsmeganisme is nie. Ons resultate het ook gewys dat RPO-aanvulling fosforilering van p38 en PKB/Akt verhoog, fosforilering van JNK verminder en PARP kliewing onderdruk. Dit dui op beskerming van die sel teen apoptose. Ons resultate dui aan dat die miokardiale beskerming wat RPO-dieet aanvulling bied moontlik geassosieer kan word met sy anti-oksidant eienskap en/of veranderinge in die vetsuur samestelling van die miokardium tydens isgemie/herperfusie. Ons het ook vir die eerste keer bewys dat RPO-aanvulling die geïsoleerde geperfuseerde werkende rothart gedurende herperfusie beskerm teen isgemie/herperfusie besering deur die aktivering en/of deaktivering van die MAPK afhanklike pad.
Navarro, Alex. "Clinical assessment of renal ischaemic injury and the role of cryopreservation : peritoneal cooling in non-heart-beating donation and topical cooling for laparoscopic surgery". Thesis, University of Sunderland, 2009. http://sure.sunderland.ac.uk/3313/.
Pełny tekst źródłaManga-Manguiya, Edith Sylvie. "Signalling pathways involved in insulin cardioprotection : are they comparable in normoxic perfused isolated rat heart vs. ischaemia/reperfusion model?" Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/17380.
Pełny tekst źródłaENGLISH ABSTRACT: Introduction: It is well documented that insulin offers cardioprotection against the consequences of ischaemia/reperfusion injury. Insulin-induced improvements in cardiac functions are widely investigated in models of ischaemia and reperfusion. It has been shown that many signalling pathways may be involved in the cardioprotection properties of insulin under those conditions. These pathways include PI3-K, PKB/Akt, p70S6k, ERK and many others. However, little data exists on the effects of insulin on the heart under normoxic condition. Some evidence has been presented that insulin has a positive inotropic effect on the normoxic perfused rat heart, but no precise cellular mechanism has been investigated or described in this regard. We believe that an investigation into the effects of insulin on cardiac function and pathways involved under normoxic conditions may help us to better understand the mechanisms of insulin-induced cardioprotection. Aims: To determine a suitable dose of insulin at which a positive inotropic response could be detectable under normoxic conditions, to investigate the possible mechanisms involved in insulin-induced increases in contractility with specific reference to the vasculature and the coronary flow and to investigate a possible involvement of PI3-K and its downstream effectors on the insulin effects on cardiac functions under normoxic conditions. Materials and methods: Isolated rat hearts were perfused retrogradely using the Langendorff technique. After 10 minutes of stabilization hearts were perfused for 30 minutes either with standard perfusion solution i.e. Krebs-Henseleit buffer + glucose gassed with 95%O2, 5%CO2 (control hearts), or with standard perfusion solution plus insulin alone or insulin together with the nitric oxide synthase inhibitor L-NAME or the PI3-K inhibitor wortmannin. Left ventricular developed pressure (LVDevP), heart rate (HR) and coronary flow (CF) as well as phosphorylated PI3-K and PKB/Akt in heart were measured. Results: Administration of insulin alone at physiological concentrations showed improved cardiac function compared to hearts in the control group. Hearts that received insulin+L-NAME showed a significant decrease in function compared to the control hearts and the hearts that received insulin alone (p<0.05). Phosphorylated PKB/Akt (Thr308) was increased in hearts that received insulin alone and insulin+L-NAME compared to the control hearts. Phosphorylated PI3-K tended to be higher in hearts where insulin was administered alone compared to the hearts that received insulin+L-NAME or insulin+wortmannin. Conclusion: This study confirmed that physiological concentrations of insulin exert positive inotropic effects on cardiac function in normoxic perfused rat hearts as seen with the improved LVDevP. Inhibition of PI3-K by wortmannin induced a decrease in phosphorylated PKB/Akt in hearts that received insulin+wortmannin and administration of L-NAME impaired the beneficial effects of insulin on cardiac functions. Therefore these results may indicate that nitric oxide may have a role in the positive effect of insulin on cardiac function in the healthy heart perfused under normoxic conditions. L-NAME as well as wortmannin reversed the positive inotropic effects of insulin. Both inhibitors also unmasked effects of insulin via nitric oxide and PI3-K on heart rate and coronary flow.
AFRIKAANSE OPSOMMING: Inleiding: Dit is welbekend dat toediening van insulien die hart beskerm teen ischemie/reperfusie-beserings, wat lei tot verbeterde hartfunksie. Hierdie effek word wyd ondersoek in modelle van ischemie en reperfusie. Dit is bewys dat ‘n verskeidenheid seintransduksie paaie, insluitend PI3-K, PKB/Akt, p70S6k en ERK, betrokke is by hierdie beskermende effek van insulien op die hart. Baie min data is egter beskikbaar rakende die effek van insulien tydens normoksiese toestande. Alhoewel dit bekend is dat insulien ’n inotropiese effek op die normale geperfuseerde hart het, is die presiese sellulêre meganismes wat dit bewerkstellig nog nie nagevors nie. Om dus ‘n beter begrip van hierdie meganismes te verkry is dit dus noodsaaklik om die effekte van insulien onder normoksiese perfusie toestande na te vors. Doelstellings: Om ‘n geskikte dosis, waarby insulien sy positiewe inotropiese effek onder normale toestande het, vas te stel, om die moontlike meganismes betrokke by insulien-geïnduseerde verbetering in hartsametrekbaarheid te bestudeer, met spesifieke verwysing na die bloedvoorsiening en koronêre vloei, en om die moontlike betrokkenheid van die PI3-K pad en sy teiken effektore onder normale suurstof-toestande te ondersoek. Materiaal en metodes: Geïsoleerde rotharte is geperfuseer deur gebruik te maak van die Langendorff tegniek. Na ‘n stabilisasie periode van 10 minute is rotharte blootgestel aan 30 minute perfusie met een van vier oplossings: ‘n standaard perfusie oplossing (Krebs-Henseleit buffer met glukose onder spesifieke gaskondisies van 95% O2, 5% CO2 – kontrole harte); standaard perfusie oplossing en insulien; standaard perfusie oplossing met insulien en die stikstofoksied sintase inhibitor L-NAME, of standaard perfusie oplossing, met insulien en die PI3-K inhibitor wortmannin. Met verloop van die perfusie protokol, is ontwikkelde linker ventrikulêre druk (LVDevP), harttempo (HR) en koronêre vloei (CF), sowel as PI3-K en PKB/Akt fosforilasie, gemeet. Resultate: Toediening van insulien teen fisiologiese konsentrasies het ‘n verbeterde hartfunksie tot gevolg, in vergelyking met harte in die kontrole groep. In teenstelling hiermee het harte wat insulien+L-NAME ontvang het ‘n betekenisvolle verlaagde funksie getoon in vergelyking met die kontrole harte en harte wat slegs insulien ontvang het (p<0.05). Harte wat slegs insulien, of insulien+L-NAME ontvang het, het ‘n verhoging in gefosforileerde PKB/Akt (Thr308) getoon in vergelyking met kontrole harte. Gefosforileerde PI3-K het ook geneig om hoër te wees in harte wat insulien+L-NAME of insulien+wortmannin ontvang het, as in harte wat slegs insulien ontvang het. Gevolgtrekking: Hierdie studie bewys dat fisiologiese konsentrasies van insulien, onder normale suurstof-toestande, ‘n positiewe inotropiese effek op hartfunksie uitoefen, soos gesien in die verbeterde LVDevP. Wortmannin-geïnduseerde inhibering van die PI3-K pad het ‘n verlaagde PKB/Akt fosforilasie tot gevolg gehad in harte wat insulien+wortmannin ontvang het, terwyl die toediening van L-NAME die voordelige effekte van insulien op hartfunksie onderdruk het. Hierdie resultate dui dus aan dat stikstofoksied ‘n rolspeler is in die positiewe inotropsiese effek van insulien op hartfunksie tydens normoksiese toestande, aangesien beide inhibitore hierdie effek onderdruk het. Beide inhibitore het ook die betrokkenheid van stikstofoksied en die PI3-K pad by die effek van insulien op harttempo en koronêre vloei onthul.
Yu, Che-kwan. "Remifentanil induces delayed cardioprotection in the rat against ischaemic and reperfusion injury via Kappa, delta, mu opioid receptors and inducible heat shock protein 70". Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B39634395.
Pełny tekst źródłaYu, Che-kwan, i 俞治均. "Remifentanil induces delayed cardioprotection in the rat against ischaemic and reperfusion injury via Kappa, delta, mu opioid receptorsand inducible heat shock protein 70". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39634395.
Pełny tekst źródłaNduhirabandi, Frederic. "The effects of chronic melatonin treatment on myocardial function and ischaemia and reperfusion injury in a rat model of diet-induced obesity". Thesis, Stellenbosch : Stellenbosch University, 2010. http://hdl.handle.net/10019.1/4493.
Pełny tekst źródłaENGLISH ABSTRACT: Obesity is a major risk factor for ischaemic heart disease. Obesity-induced metabolic abnormalities have been associated with increased oxidative stress which may play an important role in the increased susceptibility to myocardial dysfunction and ischaemiareperfusion (I/R) injury seen in obesity. The pineal gland hormone, melatonin, has powerful antioxidant properties. Previous studies have shown that short-term or acute melatonin administration protects the normal healthy heart of lean animals against I/R damage. However, the effects of melatonin on the heart in obesity remain unknown. Moreover, the myocardial signalling mechanisms associated with the cardioprotective effects of melatonin have not been established. Using a rat model of diet induced obesity, we set out to: 1) investigate the effects of chronic melatonin administration on the development of diet-induced systemic alterations including biometric and metabolic parameters and oxidative stress, 2) determine whether chronic melatonin treatment protects the myocardium against ischaemia-reperfusion injury, and 3) determine whether melatonin treatment confers cardioprotection by altering the reperfusion injury salvage kinase (RISK) pathway signalling and the pro-apoptotic p38 MAPK, AMPK and GLUT-4 expression. Male rats weighing 200±20g were randomly allocated to four groups: 1) C, control rats receiving a standard commercial rat chow and drinking water without melatonin; 2) CM, control rats receiving melatonin (4mg/kg/day) in drinking water; 3) D, diet-induced obesity rats, receiving a high calorie diet and drinking water without melatonin; 4) DM, diet-induced obesity rats, receiving melatonin in drinking water. After 16 weeks of treatment and feeding, rats were weighed and blood and myocardial tissue collected to document biochemical and molecular biological changes. Hearts were perfused on the isolated working rat heart perfusion apparatus for the evaluation of myocardial function and infarct size. The Reperfusion Injury Salvage Kinases (RISK) pathway (PKB/Akt (Ser-473), ERK p42/ p44) and p38 MAPK (mitogenactivated protein kinase) were investigated in pre-and post-ischaemic hearts using Western blotting techniques. Post-ischaemic activation of AMPK (5’AMP-activated protein kinase) (Thr- 172) and GLUT-4 (glucose transporter) expression were also investigated. Serum and baseline myocardial glutathione (GSH) content were measured. In addition, serum lipid peroxidation products: thiobarbituric reactive substances (TBARS), conjugated dienes (CD) and lipid hydroperoxide (LOOH), were also determined. The high-calorie diet caused increases in body weight, visceral adiposity, heart weight, serum insulin, leptin, blood triglycerides, and low HDL-cholesterol levels. Blood glucose levels were similar for both diet fed rats and controls. Myocardial glutathione, serum glutathione, total cholesterol, TBARS, LOOH, CD as well as total cholesterol (TC) levels were not affected by the high calorie diet. Chronic melatonin treatment reduced body weight gain, visceral adiposity, heart weight, blood triglycerides, serum insulin, HOMA index, serum leptin (DM vs D, p<0.01), and increased blood HDL-C in diet treated rats while there was no effect on these parameters in control rats, despite the reduction in body weight, heart weight and visceral adiposity. Melatonin treatment had no effect on myocardial or serum GSH and LOOH in either control or diet animals. It however reduced TBARS and CD in the diet and control groups, respectively. At baseline, chronic melatonin treatment caused a significant increase in phospho-PKB/total PKB ratio and a concomitant reduction in phospho-p38 MAPK/total p38 MAPK ratio of control hearts while there were no such effects on diet-induced-obesity hearts. Infarct size was significantly reduced by melatonin in both diet and control groups (DM: 16.6±2.0%; D: 38.4±2.6% (p < 0.001), and CM: 12.8±1.5%; C: 30.4±1.0%, p<0.001). After coronary artery occlusion and 30 minutes of reperfusion, melatonin increased percentage recovery of aortic output (DM: 28.5±6.5%; D: 6.2±6.2%, p<0.01), cardiac output (DM: 44.4±5.2%; D: 26.6±5.1%, p < 0.01) and total work (DM: 34.5±5.6%; D: 20.4±7.9%, p<0.05) of diet-induced obesity hearts, while having no effect on control hearts. During reperfusion, hearts from melatonin treated rats had increased activation of PKB/Akt (p<0.01), ERK42/44 (p<0.05), and reduced p38 MAPK activation (p<0.05). There was no difference in post-ischaemic activation of AMPK (Thr-172) and GLUT-4 expression in either control or diet fed rats. We successfully demonstrated that chronic melatonin treatment prevented the development of diet-induced metabolic abnormalities and improved ex vivo myocardial function. Melatonin protected the heart against ischaemia-reperfusion injury that was exacerbated in obesity. This was achieved by activation of the RISK pathway. The antioxidant properties of melatonin were involved in these cardioprotective effects.
AFRIKAANSE OPSOMMING: Vetsug of obesiteit is een van die hoof risikofaktore vir iskemiese hartsiekte. Obesiteitgeinduseerde metaboliese abnormaliteite gaan met verhoogde oksidatiewe stres gepaard wat op sy beurt ‘n belangrike rol mag speel in die miokardiale wanfunksie en verhoogde vatbaarheid vir iskemie-herperfusie (I/H) beskadiging, kenmerkend van vetsug. Melatonien, die hormoon afgeskei deur die pineaalklier, is ‘n kragtige anti-oksidant. Vorige studies het getoon dat kort-termyn of akute toediening van melatonien die normale hart van gesonde diere teen I/H beskadiging deur middel van sy anti-oksidant aksies beskerm. Die effek van melatonien op die hart in obesiteit is egter nog onbekend. Hierbenewens is die miokardiale seintransduksie meganismes geassosieer met die beskermende effekte van die hormoon nog nie ontrafel nie. ‘n Model van dieet-geinduseerde obesiteit in rotte is gebruik om die volgende te bepaal: (i) die effek van kroniese melatonientoediening op die ontwikkeling van dieet-geinduseerde sistemiese veranderinge soos biometriese en metaboliese parameters en oksidatiewe stres (ii) die effek van kroniese melatonienbehandeling op die respons van die hart op I/H beskadiging en (iii) die rol van herperfusie beskadiging op die aktivering van PKB/Akt en ERK42/44 (die sg RISK seintransduksiepad), die pro-apoptotiese p38MAPK, AMPK sowel as die uitdrukking van GLUT-4. Manlike Wistar rotte (200±20g) is ewekansig in vier groepe verdeel: (i) C, kontrole rotte wat ‘n standaard rotdieet en drinkwater sonder melatonien ontvang (ii) CM, kontrole rotte wat melatonien (4mg/kg/dag) ontvang (iii) D, dieet-geϊnduseerde vet rotte wat ‘n hoë kalorie dieet en drinkwater sonder melatonien ontvang (iv) DM, dieet-geϊnduseerde vet rotte wat melatonien (4mg/kg/dag) in die drinkwater ontvang. Na 16 weke van behandeling, is die rotte geweeg, bloed en hartweefsel gekollekteer vir biochemiese en molekulêre biologie bepalings. Harte is geperfuseer volgens die werkhartmodel, blootgestel aan iskemie/herperfusie vir evaluering van funksionele herstel en infarktgrootte. Uitdrukking en aktivering van PKB/Akt (Ser-473), ERKp42/p44 en p38MAPK van pre-en postiskemiese hartweefsel is met behulp van Western blot bepaal. Postiskemiese aktivering van AMPK (5’AMP-aktiveerde proteϊen kinase) (Thr-172) en GLUT-4 (glukose transporter) is op soortgelyke wyse bepaal. Serum en basislyn hartweefsel glutatioon (GSH) inhoud asook tiobarbituursuur reaktiewe substans (TBARS), gekonjugeerde diene (CD) en lipiedhidroperoksied (LOOH) konsentrasies is bepaal. Resultate Die hoë kalorie diet het ‘n toename in liggaamsgewig, visserale vet, hartgewig, serum insulien, leptien, plasma trigliseried en lae HDL-cholesterol vlakke teweegebring. Bloed glukosevlakke was egter dieselfde in die vet en kontrole rotte. Miokardiale glutatioon, serum glutatioon, totale cholesterol, TBARS, LOOH, CD is nie deur die dieet beinvloed nie. Chroniese melatonien behandeling het die liggaamsgewig, visserale vet, hartgewig, plasma trigliseried, serum insulien en leptien, HOMA indeks verlaag (DM vs D, p<0.05) en die HDL-cholesterol verhoog in die dieetrotte, terwyl dit geen effek op hierdie parameters in kontrole rotte gehad het nie (uitgesonderd ‘n afname in liggaamsgewig, hartgewig en visserale vet). Melatonien behandeling het geen effek op hart of serum GSH en LOOH in kontrole en vet rotte gehad nie. Dit het egter die TBARS en CD in beide vet en kontrole rotte verlaag. Chroniese melatonien toediening het ‘n beduidende toename in basislyn fosfo PKB//totale PKB ratio en ‘n afname in fosfo p38MAPK/totale p38MAPK ratio teweegebring in harte van kontrole rotte, maar soortgelyke effekte is nie in die harte van die vet rotte waargeneem nie. Infarktgrootte is beduidend deur melatonienbehandeling verlaag in beide dieet en kontrole groepe (DM: 16.6± 5.2%, D: 38.4 ±2.6% (p<0.001); CM: 12.8± 1.5%; C 30.4±1.0 (p<0.001). Na koronere arterie afbinding en 30 min van herperfusie, het melatonien die persentasie herstel van aorta omset (DM: 28.5± 6.5%; D: 6.2± 6.2%, p<0.01), kardiale omset ( DM: 44.4± 5.2%D: 26.6±5.1%, p<0.01) en totale werk (DM: 34.5 5.6%; D 20.4± 7.9%, p<0.05) in die harte van dieetrotte verbeter, terwyl dit sonder effek was in kontrole harte. Tydens herperfusie het harte van melatonienbehandelde rotte verhoogde aktivering van PKB/Akt (p<0.01) en ERKp42/p44 (p<0.05) getoon, terwyl aktivering van p38MAPK verlaag is (p<0.05). Geen verskil in postiskemiese aktivering van AMPK en GLUT-4 uitdrukking is in beide kontrole en dieetrotte waargeneem nie. Ons het daarin geslaag om aan te toon dat chroniese melatonienbehandeling die ontwikkeling van dieet-geϊnduseerde metaboliese abnormaliteite beduidend kan voorkom en ex vivo miokardiale funksie verbeter. Melatonien het ook die hart teen iskemie/herperfusie beskadiging beskerm in beide kontrole en dieetrotte. Bogenoemde veranderinge het met aktivering van PKB/Akt en ERKp42/p44 gepaard gegaan. Die anti-oksidant effekte van melatonien was heelwaarskynlik hierby betrokke.
Hing, Alfred Victor Chang Cardiac Research Institute Faculty of Medicine UNSW. "Optimising the quality of donor organs for transplantation: studies of hormone resuscitation of the brain-dead multi-organ donor and the development of a long-term preservation strategy to optimise function of the transplanted heart in a porcine model". Awarded by:University of New South Wales. Victor Chang Cardiac Research Institute, 2009. http://handle.unsw.edu.au/1959.4/44792.
Pełny tekst źródłaBester, Dirk Jacobus. "The effect of red palm oil supplementation of an oxidative risk induced diet and a high saturated fat diet on ischaemia/perfusion injury in the isolated perfused rat heart". Thesis, Cape Peninsula University of Technology, 2006. http://hdl.handle.net/20.500.11838/1470.
Pełny tekst źródłaResearch has shown that the activation of the NO-cGMP pathway leads to myocardial protection from oxidative stress conditions, such as ischaemia and reperfusion. Few of these studies have however combined diet induced oxidative stress with ischaemia/reperfusion injury. Although little is known about the effects of supplements such as red palm oil (RPO) on the NO-cGMP pathway, research has shown that dietary RPO-supplementation improved reperfusion aortic output recovery through mechanisms that may include activation of the NO-cGMP- and inhibition of the cAMP pathway. RPO is an antioxidant-rich oil containing ~carotene and Vitamin E (tocopherols and tocotrienols). The aims of this study were to determine: 1) whether RPO-supplementation of an oxidative risk induced diet (ORD) and a high saturated fat diet (HFD) offers protection against ischaemia/reperfusion injury in the isolated perfused rat heart and 2) the possible mechanisms for this protection. Male Wistar rats were randomly divided into four groups for a period of 14 weeks according to the dietary supplementation they received. The control groups received either an oxidative risk induced diet (ORD) or a high saturated fat diet (HFD), while the experimental groups received an ORD supplemented with RPO (ORD+RPO) or a HFD supplemented with RPO (HFD+RPO).
Thamahane-Katengua, Emma Tutu Masechela. "Effect of rooibos and red palm oil supplementation, alone or in combination, on cardiac function after exposure to hypertension and inflammation in an ischaemial/reperfusion injury model". Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/1520.
Pełny tekst źródłaCardiovascular disease (CVD) is without a doubt one of the most challenging health issues of our time and accounts for the highest number of deaths in both developed and developing countries. Despite the huge strides that have been achieved in the diagnosis and therapeutic intervention of CVD, the disease burden still remains enormous. Therefore, this calls for novel and innovative interventions to curb the surge of CVD. The use of plant based food with bioactive phytochemicals,has a great potential to reduce the incidence of CVD, specifically in resource-strained countries. Red palm oil (RPO) and the indigenous herbal tea, rooibos have previously been shown to exhibit potential cardioprotective effects. Their health promoting properties have largely been attributed to their antioxidant and anti-inflammatory activities and emerging evidence also showed that they have the potential to modulate cell signalling events. Substancial scientific evidence proposes oxidative stress and inflammation to play an important role in the pathogenesis of cardiovascular disease. Hence, natural plant extracts such as RPO and rooibos could be recommended as adjuvants to clinical therapy to reduce the morbidity and mortality associated with CVD. This thesis reports on three studies investigating the cardiovascular protective effects that chronic feeding of either RPO, rooibos or their combination have on 1) antioxidant enzymes and the NO-cGMP pathway in myocardial tissue of spontaneous hypertensive rats, 2) the modulation of systemic and myocardial inflammation and 3) the myocardial ischaemic/reperfusion tolerance in a rat model of lypopolysaccharide induced inflammation. The aim of the first study was to investigate the effect of RPO on cardiac function in sponteneously hypertensive rats. The role of the nitric oxide cyclic-guanosine monophosphate(NO-cGMP) pathway, (as determined by the nitric oxide (NOS) activity) and the antioxidant defence system (selected antioxidant enzymes) were also investigated. Cardiac function was monitored at stabilization and reperfusion using the Langendorff perfusion system. Antioxidant enzymes were determined from left ventricular tissue, while total NOS activity was determined in the aorta and left ventricular tissue. The results show that RPO offered cardiac protection as evidenced by improved left ventricular developed pressure (LVDevP), maximum velocity of pressure rise (+dp/dt) max and fall (-dp/dt) max during reperfusion in sponteneously hypertensive rats (SHR) compared to their control counterparts. Improved function in SHR was associated with increased myocardial superoxide dismutase 2 (SOD2) protein expression compared to the normotensive rats. There was differential modulation of the NOS activity by RPO, an increase in NOS activity was observed in the aorta while a reduction in the activity of NOS was observed in the left ventricular tissue of both RPO supplemented normotensive and hypertensive rats compared to their respective control groups. These results argue a role for elevated NO production in the aorta for endothelial function maintenance. Increased SOD2 protein might lead to reduced oxidative stress. Thus, NO-cGMP pathway and antioxidant defense systems synergistically acted to restore cardiovascular function in SHR. The aim of the second study was to investigate the effect of RPO and rooibos supplementation on the modulation of systemic and myocardial inflammation in a rat model. As RPO and rooibos contain different types of antioxidants which reside and exert their biological effects in different cellular compartments, the combination of these two natural food compounds has the potential to enhance the spectrum of available dietary antioxidants in different cellular compartments, which could result in a better protection against certain pathological conditions such as inflammation. The Langendorff system and the lypopolysaccharide (LPS)-induced inflammatory model were used to determine if RPO and rooibos could protect against the negative effect of LPS-induced inflammation on baseline cardiac function. Both inflammation and dietary supplementation did not have any effect on baseline cardiac functional parameters. Our results show that administration of LPS resulted in elevated plasma levels of IL-1β in supplemented and non-supplemented rats indicating that an inflammatory response was triggered in the LPS-treated rats. However, this increase in IL-1β was counteracted by concurrent elevation of plasma IL-10 in LPS-induced rats consuming either rooibos or RPO alone. Furthermore the combination of RPO and rooibos enhanced myocardial IL-10 levels in LPS-induced rats. This data shows a difference in response to LPS injection between the myocardium and the systemic circulation. The results indicate that the combination of these two natural food substances exhibit potential anti-inflammatory properties which could be beneficial in clinically relevant conditions where inflammation plays a role. Having shown that dietary intervention with RPO and rooibos had the potential to modulate the inflammatory response in the model of inflammation at basal conditions, we then proceeded to the third study to specifically establish if dietary RPO when supplemented alone will improve functional recovery and reduce infarct size in LPS-treated hearts. The Langendorff perfusion system was employed for determination of cardiac function and infarct size. The roles of NFkB, p38 MAPK and the myocardial antioxidant defence systems were investigated as potential mechanisms of protection. LPS-treatment caused significant increases in myocardial IL-1 β indicating that inflammation was induced. However, the levels of myocardial IL-10 was reduced in LPS-treated hearts compared to the non-treated hearts. Intervention with dietary RPO resulted in improved functional recovery and reduced infarct size, in both healthy hearts and in the LPS-treatment group. The RPO-induced cardio-protection was associated with increases in myocardial protein expression of the antioxidant enzymes, SOD1, SOD2, GPX1 as well as increased p38 phosphorylation during reperfusion. LPS treatment increased myocardial protein expression of NFkB p65 which was reversed by RPO supplementation. Reduction of myocardial NFkB protein expression, increased p38 phosphorylation and elevated mitochondrial antioxidant (SOD2 and GPX1) as well as cytosolic enzymes (SOD 1) are proposed as potential mechanisms underlying the RPO-induced cardio-protection in this model. Based on these study results, for the first time, having included vasculature aspects in the cardio-protective effects of RPO we have shown that the NO-cGMP pathway and antioxidant defense systems may act synergistically to restore cardiovascular function in spontaneously hypertensive rats. Results from the second study also provide the first scientific evidence that RPO in combination with rooibos (a flavonoid rich endemic herbal tea) could have potential anti-inflammatory activities at systemic as well as myocardial level, which may be beneficial in clinically relevant conditions where inflammation plays a role. From the third study it can be concluded that dietary RPO improved myocardial tolerance to ischaemia-reperfusion injury in a model of inflammation.
Wilkinson, Dominic James Clifford. "Ethical issues in the use of magnetic resonance imaging of the brain in newborn infants with hypoxic-ischaemic encephalopathy : neuroimaging and decision-making for brain injured newborns". Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:d61e4318-3568-4310-bf92-c7d70f2cb3da.
Pełny tekst źródłaBattin, Malcolm Richard. "Selective cerebral hypothermia for term infants following hypoxic ischaemic injury". 2008. http://hdl.handle.net/2292/5545.
Pełny tekst źródłaWhole document restricted until 11/2014, but available by request, use the feedback form to request access.
Vermeulen, Michelle. "The role of MKP-1 in autophagy, apoptosis and necrosis during ischaemia/reperfusion injury in the heart". Thesis, 2010. http://hdl.handle.net/10019.1/5181.
Pełny tekst źródłaENGLISH ABSTRACT: Ischaemic heart disease is a leading cause of death worldwide and is also largely contributing to deaths in Africa. Better treatment or even prevention of ischaemia/reperfusion injury in the heart, necessitates a better understanding of the molecular pathways and mechanisms of cell death. Three types of cell death can occur in the diseased myocardium. Type I, better known as apoptotic cell death, is characterised by cell shrinkage and chromatin condensation, type II, known as autophagic cell death, is characterised by intracellular accumulation of double membranes vacuoles and type III, necrotic cell death, is characterised by cellular swelling and loss of membrane integrity. Many signaling pathways are activated during ischaemia/reperfusion injury which include the mitogen activated protein kinases (MAPKs), such as extracellular signal-regulated protein kinase (ERK), c-Jun NH2-terminal protein kinase (JNK) and p38 MAPK. These kinases are dephosphorylated by appropriate phosphatases. MAPK phosphatase-1 (MKP-1), a dual specificity phosphatase, inactivates the MAPKs by dephosphorylating specific Thr/Tyr residues. Upregulation of MKP-1 during ischaemia/reperfusion injury has been shown to be cardioprotective, however no knowledge regarding a role of MKP-1 in autophagy exists. Therefore the aim of this study is to investigate the role of MKP-1 in autophagy, apoptosis and necrosis during simulated ischaemia/reperfusion injury in the heart.METHOD: H9C2 cells (rat cardiomyocytes) were cultured under standard conditions. Upon reaching 75-80% confluency, cells were treated for 30 min during normoxic conditions with dexamethasone, to induce MKP-1 expression, or sanguinarine, to inhibit MKP-1 induction. Thereafter, they were exposed to 3 hrs simulated ischaemia (induced by an ischaemic buffer and 5% CO2/1% O2) in the presence of the above mentioned treatments. Cells were then allowed to reperfuse for 30 min in the presence of dexamethasone or sanguinarine. Samples were analysed after simulated ischaemia and after reperfusion. Cell viability was measured by MTT assay. Propidium iodide and Hoechst staining were used to assess morphological markers of apoptosis and necrosis. LDH release during reperfusion was assessed as indicator of necrotic cell death. LysoTracker®Red was used to visualise the autophagic flux occurring during ischaemia/reperfusion in the cell. Flow cytometry was used to quantify cells stained with acridine orange as indicator for autophagy. Autophagic and apoptotic protein markers as well as MAPK and MKP-1 activity were analysed by Western Blotting. RESULTS: Our results indicate a clear relationship between MKP-1 induction, autophagy and cell survival during simulated ischaemia/reperfusion (SI/R). MKP-1 inhibition during SI/R resulted in decreased autophagy activity accompanied by significant apoptotic and necrotic cell death. Increased MKP-1 induction, on the other hand, during SI/R resulted in increased levels of autophagy activity and subsequent attenuation of apoptotic and necrotic cell death. p38 MAPK phosphorylation was significantly higher while MKP-1 was inhibited and significantly lower while MKP-1 was induced. This strongly indicates that upregulation of MKP-1, known to attenuate ischaemia/reperfusion injury, has an important role in cell survival during ischaemia/reperfusion injury in the heart, through its involvement in the regulation of autophagic activity as a stress response against apoptotic or necrotic cell death.
AFRIKAANSE OPSOMMING: Iskemiese hartsiekte is een van die grootste oorsake van sterftes wêreldwyd en dra ook beduidend by tot sterftes in Afrika. Om iskemiese hartsiektes te behandel of selfs te voorkom, is 'n goeie begrip van die molekulêre paaie wat betrokke is tydens iskemie/herperfusie, noodsaaklik. Drie tipes seldood kom tydens patologiese toestande in die hart voor. Tipe I, ook bekend as apoptotiese seldood, word gekenmerk deur selkrimping en kromatien kondensasie, tipe II, ook bekend as autofagiese seldood word gekenmerk deur intrasellulêre opeenhoping van dubbelmembraan vakuole en tipe III, bekend as nekrotiese seldood, word deur sellulêre swelling en verlies van membraan integriteit gekenmerk. Iskemie/herperfusie lei tot die aktivering van seintransduksiepaaie wat die MAPKs, soos p38, ERK en JNK insluit. Hierdie kinases word deur die gepaste fosfatases gedefosforileer. MKP-1, 'n dubbele spesifieke fosfatase, deaktiveer MAPKs deur hul Thr/Tyr eenhede te defosforileer. Alhoewel daar al voorheen getoon is dat verhoogte MKP-1 ‘n beskermende funksie in die hart tydens iskemie/herperfusie het, is daar nog geen bewyse vir ‘n rol van MKP-1 tydens autofagie nie. Die doel van hierdie studie is dus om die rol van MKP-1 in autofagie, apoptose en nekrose te ondersoek tydens gesimuleerde iskemie/herperfusie in die hart. METODE: H9C2 selle (rot ventrikulêre hartselle) is onder standaard toestande gekweek. Wanneer die selle 75-80% konfluensie bereik het, is dit behandel met dexamethasone of sanguinarine onder standaard toestande vir 30 min. Daarna is selle blootgestel aan 3 ure iskemie, in die teenwoordigheid van dexamethasone of sanguinarine. Selle is dan toegelaat om vir 30 min te herperfuseer, weer in die teenwoordigheid van dexamethasone of sanguinarine. Monsters is na iskemie en herperfusie geneem vir analise. Selvatbaarheid is gekwantifiseer deur ‘n MTT bepaling. Morfologiese merkers van seldood is bepaal met behulp van propidium iodide en Hoechst kleuringsmetodes. Laktaatdehidrogenase (LDH) vrystelling tydens herperfusie is as merker van nekrose gebruik. Autofagie is gevisualiseer deur gebruik te maak van LysoTracker®Red kleuring tydens iskemie en herperfusie. Akridienoranje is gebruik om suur kompartemente te kleur. Vloeisitometrie is as kwantifiseringstegniek vir autofagie gebruik. Western Blotting is gebruik om uitdrukking van merkerproteïene van autofagie en apoptose sowel as MAPK en MKP-1 aktiwiteit tydens iskemie/reperfisie te bepaal. RESULTATE: Ons resultate toon ‘n verband tussen MKP-1 induksie, autofagie en seloorlewing gedurende gesimuleerde iskemie/herperfusie (SI/R) aan. MKP- 1 inhibisie gedurende SI/R het tot ‘n afname in autofagie gelei tesame met ‘n beduidende toename in apoptotiese en nekrotiese seldood. Verhoogde MKP-1 induksie gedurende SI/R, daarteenoor, het autofagiese aktiwiteit verhoog, gepaardgaande met ‘n verlaging in apoptose en nekrose. p38 MAPK fosforilasie was beduidend hoër tydens MKP-1 inhibisie en laer met MKP-1 induksie. Hierdie resultate toon dat MKP-1 ‘n belangrike rol in seloorlewing speel tydens iskemie/herperfusiesskade in die hart, deur sy deelname in die regulering van autofagiese aktiwiteit as ‘n stres reaksie teen apoptotiese en nekrotiese seldood.