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Academic literature on the topic 'Na+/Ca2+ exchanger'

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Journal articles on the topic "Na+/Ca2+ exchanger"

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Matsuoka, S., D. A. Nicoll, L. V. Hryshko, D. O. Levitsky, J. N. Weiss, and K. D. Philipson. "Regulation of the cardiac Na(+)-Ca2+ exchanger by Ca2+. Mutational analysis of the Ca(2+)-binding domain." Journal of General Physiology 105, no. 3 (March 1, 1995): 403–20. http://dx.doi.org/10.1085/jgp.105.3.403.

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The sarcolemmal Na(+)-Ca2+ exchanger is regulated by intracellular Ca2+ at a high affinity Ca2+ binding site separate from the Ca2+ transport site. Previous data have suggested that the Ca2+ regulatory site is located on the large intracellular loop of the Na(+)-Ca2+ exchange protein, and we have identified a high-affinity 45Ca2+ binding domain on this loop (Levitsky, D. O., D. A. Nicoll, and K. D. Philipson. 1994. Journal of Biological Chemistry. 269:22847-22852). We now use electrophysiological and mutational analyses to further define the Ca2+ regulatory site. Wild-type and mutant exchangers were expressed in Xenopus oocytes, and the exchange current was measured using the inside-out giant membrane patch technique. Ca2+ regulation was measured as the stimulation of reverse Na(+)-Ca2+ exchange (intracellular Na+ exchanging for extracellular Ca2+) by intracellular Ca2+. Single-site mutations within two acidic clusters of the Ca2+ binding domain lowered the apparent Ca2+ affinity at the regulatory site from 0.4 to 1.1-1.8 microM. Mutations had parallel effects on the affinity of the exchanger loop for 45Ca2+ binding (Levitsky et al., 1994) and for functional Ca2+ regulation. We conclude that we have identified the functionally important Ca2+ binding domain. All mutant exchangers with decreased apparent affinities at the regulatory Ca2+ binding site also have a complex pattern of altered kinetic properties. The outward current of the wild-type Na(+)-Ca2+ exchanger declines with a half time (th) of 10.8 +/- 3.2 s upon Ca2+ removal, whereas the exchange currents of several mutants decline with th values of 0.7-4.3 s. Likewise, Ca2+ regulation mutants respond more rapidly to Ca2+ application. Study of Ca2+ regulation has previously been possible only with the exchanger operating in the reverse mode as the regulatory Ca2+ and the transported Ca2+ are then on opposite sides of the membrane. The use of exchange mutants with low affinity for Ca2+ at regulatory sites also allows demonstration of secondary Ca2+ regulation with the exchanger in the forward or Ca2+ efflux mode. In addition, we find that the affinity of wild-type and mutant Na(+)-Ca2+ exchangers for intracellular Na+ decreases at low regulatory Ca2+. This suggests that Ca2+ regulation modifies transport properties and does not only control the fraction of exchangers in an active state.
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Hryshko, L. V., S. Matsuoka, D. A. Nicoll, J. N. Weiss, E. M. Schwarz, S. Benzer, and K. D. Philipson. "Anomalous regulation of the Drosophila Na(+)-Ca2+ exchanger by Ca2+." Journal of General Physiology 108, no. 1 (July 1, 1996): 67–74. http://dx.doi.org/10.1085/jgp.108.1.67.

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The Na(+)-Ca2+ exchanger from Drosophila was expressed in Xenopus and characterized electrophysiologically using the giant excised patch technique. This protein, termed Calx, shares 49% amino acid identity to the canine cardiac Na(+)-Ca2+ exchanger, NCX1. Calx exhibits properties similar to previously characterized Na(+)-Ca2+ exchangers including intracellular Na+ affinities, current-voltage relationships, and sensitivity to the peptide inhibitor, XIP. However, the Drosophila Na(+)-Ca2+ exchanger shows a completely opposite response to cytoplasmic Ca2+. Previously cloned Na(+)-Ca2+ exchangers (NCX1 and NCX2) are stimulated by cytoplasmic Ca2+ in the micromolar range (0.1-10 microM). This stimulation of exchange current is mediated by occupancy of a regulatory Ca2+ binding site separate from the Ca2+ transport site. In contrast, Calx is inhibited by cytoplasmic Ca2+ over this same concentration range. The inhibition of exchange current is evident for both forward and reverse modes of transport. The characteristics of the inhibition are consistent with the binding of Ca2+ at a regulatory site distinct from the transport site. These data provide a rational basis for subsequent structure-function studies targeting the intracellular Ca2+ regulatory mechanism.
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Ruknudin, A., C. Valdivia, P. Kofuji, W. J. Lederer, and D. H. Schulze. "Na+/Ca2+ exchanger in Drosophila: cloning, expression, and transport differences." American Journal of Physiology-Cell Physiology 273, no. 1 (July 1, 1997): C257—C265. http://dx.doi.org/10.1152/ajpcell.1997.273.1.c257.

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cDNAs for the Na+/Ca2+ exchanger from Drosophila melanogaster (Dmel/Nck) have been cloned by homology screening using the human heart Na+/Ca2+ exchanger cDNA. The overall deduced protein structure for Dmel/Nck is similar to that of mammalian Na+/Ca2+ exchanger genes NCX1 and NCX2, having six hydrophobic regions in the amino terminus separated from six at the carboxy-terminal end by a large intracellular loop. Sequence comparison of the Drosophila exchanger cDNAs with NCX1 and NCX2 Na+/Ca2+ exchangers are approximately 46% identical at the deduced amino acid level. Consensus phosphorylation sites for both protein kinase C and protein kinase A are present on the intracellular loop region of the Dmel/Nck. Alternative splicing for the Dmel/Nck gene is suggested in the same intracellular loop region as demonstrated for NCX1. Functionally, the Drosophila Na+/ Ca2+ exchanger expressed in oocytes differs from expressed mammalian NCX1 with regard to Ca2+ transport in Ca2+/ Ca2+ exchange and the effect of monovalent-dependent Ca2+/ Ca2+ exchange. The Dmel/Nck gene maps to chromosome 3 (93A-B) using in situ hybridization to polytene chromosomes, the same position as the Na(+)-K(+)-ATPase, a related transporter. We conclude that, although extracellular Na+ concentration-dependent Ca2+ transport is subserved by both human and Drosophila Na+/Ca2+ exchangers, there are clear and important differences in the transporters, which should be useful in deducing how the Na+/Ca2+ exchanger protein function depends on its structure.
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Schoenmakers, T. J., and G. Flik. "Sodium-extruding and calcium-extruding sodium/calcium exchangers display similar calcium affinities." Journal of Experimental Biology 168, no. 1 (July 1, 1992): 151–59. http://dx.doi.org/10.1242/jeb.168.1.151.

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Na+/Ca2+ exchange activities in purely inside-out and mixed inside-out and right-side-out fish enterocyte basolateral plasma membrane vesicle preparations display equal affinities for Ca2+, showing that only the intracellular Ca2+ transport site of the Na+/Ca2+ exchanger is detected in experiments on vesicle preparations with mixed orientation. Therefore, Ca2+ pump and Na+/Ca2+ exchange activity may be compared directly without correction for vesicle orientation. The Na+/Ca2+ exchange activity in fish enterocyte vesicles is compared to the activity found in dog erythrocyte vesicles. The calcium-extruding exchanger in fish basolateral plasma membranes shows values of Km and V(max) for calcium similar to those found for the sodium-extruding exchanger in dog erythrocyte membranes, indicating that differences in electrochemical gradients underlie the difference in cellular function of the two exchangers.
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Omelchenko, Alexander, Christopher Dyck, Mark Hnatowich, John Buchko, Debora A. Nicoll, Kenneth D. Philipson, and Larry V. Hryshko. "Functional Differences in Ionic Regulation between Alternatively Spliced Isoforms of the Na+-Ca2+ Exchanger from Drosophila melanogaster." Journal of General Physiology 111, no. 5 (May 1, 1998): 691–702. http://dx.doi.org/10.1085/jgp.111.5.691.

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Ion transport and regulation were studied in two, alternatively spliced isoforms of the Na+-Ca2+ exchanger from Drosophila melanogaster. These exchangers, designated CALX1.1 and CALX1.2, differ by five amino acids in a region where alternative splicing also occurs in the mammalian Na+-Ca2+ exchanger, NCX1. The CALX isoforms were expressed in Xenopus laevis oocytes and characterized electrophysiologically using the giant, excised patch clamp technique. Outward Na+-Ca2+ exchange currents, where pipette Ca2+o exchanges for bath Na+i, were examined in all cases. Although the isoforms exhibited similar transport properties with respect to their Na+i affinities and current–voltage relationships, significant differences were observed in their Na+i- and Ca2+i-dependent regulatory properties. Both isoforms underwent Na+i-dependent inactivation, apparent as a time-dependent decrease in outward exchange current upon Na+i application. We observed a two- to threefold difference in recovery rates from this inactive state and the extent of Na+i-dependent inactivation was approximately twofold greater for CALX1.2 as compared with CALX1.1. Both isoforms showed regulation of Na+-Ca2+ exchange activity by Ca2+i, but their responses to regulatory Ca2+i differed markedly. For both isoforms, the application of cytoplasmic Ca2+i led to a decrease in outward exchange currents. This negative regulation by Ca2+i is unique to Na+-Ca2+ exchangers from Drosophila, and contrasts to the positive regulation produced by cytoplasmic Ca2+ for all other characterized Na+-Ca2+ exchangers. For CALX1.1, Ca2+i inhibited peak and steady state currents almost equally, with the extent of inhibition being ≈80%. In comparison, the effects of regulatory Ca2+i occurred with much higher affinity for CALX1.2, but the extent of these effects was greatly reduced (≈20–40% inhibition). For both exchangers, the effects of regulatory Ca2+i occurred by a direct mechanism and indirectly through effects on Na+i-induced inactivation. Our results show that regulatory Ca2+i decreases Na+i-induced inactivation of CALX1.2, whereas it stabilizes the Na+i-induced inactive state of CALX1.1. These effects of Ca2+i produce striking differences in regulation between CALX isoforms. Our findings indicate that alternative splicing may play a significant role in tailoring the regulatory profile of CALX isoforms and, possibly, other Na+-Ca2+ exchange proteins.
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Schnetkamp, Paul P. M. "Functional expression of Na–Ca exchanger clones measured with the fluorescent Ca2+-indicating dye fluo-3." Biochemistry and Cell Biology 74, no. 4 (July 1, 1996): 535–39. http://dx.doi.org/10.1139/o96-457.

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The process of Ca2+ homeostasis is of prime importance to all cells because of the ubiquitous role of cytoplasmic Ca2+ as an intracellular messenger and the cytotoxicity of sustained elevated cytosolic Ca2+ concentrations. Two classes of plasma membrane proteins are responsible for maintaining cytosolic free Ca2+ in the submicromolar range against a very large electrochemical Ca2+ gradient across the plasma membrane, the ATP-driven Ca2+ pump and Na–Ca exchangers. Two types of Na–Ca exchangers are known, the 3Na:1Ca exchangers found in heart, brain, kidney, and most other tissues and the 4Na:1Ca+1K exchanger found in retinal rod and cone photoreceptors. Functional expression of Na–Ca(/K) exchangers is most often measured as 45Ca uptake in Na+-loaded cells or as Na–Ca exchange currents with the giant excised patch technique. In this study, two functional assays used to detect expression of the bovine heart Na–Ca exchanger in CHO cells are described. Both assays are based on measurements of cytosolic free Ca2+ with the fluorescent Ca2+-indicating dye fluo-3 and should be equally applicable in the study of functional expression of both Na–Ca and Na–Ca/K exchanger clones.Key words: Na–Ca exchange, Ca homeostasis, fluo-3, ion transport, functional expression.
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Lytton, Jonathan. "Na+/Ca2+ exchangers: three mammalian gene families control Ca2+ transport." Biochemical Journal 406, no. 3 (August 29, 2007): 365–82. http://dx.doi.org/10.1042/bj20070619.

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Mammalian Na+/Ca2+ exchangers are members of three branches of a much larger family of transport proteins [the CaCA (Ca2+/cation antiporter) superfamily] whose main role is to provide control of Ca2+ flux across the plasma membranes or intracellular compartments. Since cytosolic levels of Ca2+ are much lower than those found extracellularly or in sequestered stores, the major function of Na+/Ca2+ exchangers is to extrude Ca2+ from the cytoplasm. The exchangers are, however, fully reversible and thus, under special conditions of subcellular localization and compartmentalized ion gradients, Na+/Ca2+ exchangers may allow Ca2+ entry and may play more specialized roles in Ca2+ movement between compartments. The NCX (Na+/Ca2+ exchanger) [SLC (solute carrier) 8] branch of Na+/Ca2+ exchangers comprises three members: NCX1 has been most extensively studied, and is broadly expressed with particular abundance in heart, brain and kidney, NCX2 is expressed in brain, and NCX3 is expressed in brain and skeletal muscle. The NCX proteins subserve a variety of roles, depending upon the site of expression. These include cardiac excitation–contraction coupling, neuronal signalling and Ca2+ reabsorption in the kidney. The NCKX (Na2+/Ca2+–K+ exchanger) (SLC24) branch of Na+/Ca2+ exchangers transport K+ and Ca2+ in exchange for Na+, and comprises five members: NCKX1 is expressed in retinal rod photoreceptors, NCKX2 is expressed in cone photoreceptors and in neurons throughout the brain, NCKX3 and NCKX4 are abundant in brain, but have a broader tissue distribution, and NCKX5 is expressed in skin, retinal epithelium and brain. The NCKX proteins probably play a particularly prominent role in regulating Ca2+ flux in environments which experience wide and frequent fluctuations in Na+ concentration. Until recently, the range of functions that NCKX proteins play was generally underappreciated. This situation is now changing rapidly as evidence emerges for roles including photoreceptor adaptation, synaptic plasticity and skin pigmentation. The CCX (Ca2+/cation exchanger) branch has only one mammalian member, NCKX6 or NCLX (Na+/Ca2+–Li+ exchanger), whose physiological function remains unclear, despite a broad pattern of expression.
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Rasgado-Flores, H., and M. P. Blaustein. "Na/Ca exchange in barnacle muscle cells has a stoichiometry of 3 Na+/1 Ca2+." American Journal of Physiology-Cell Physiology 252, no. 5 (May 1, 1987): C499—C504. http://dx.doi.org/10.1152/ajpcell.1987.252.5.c499.

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The portions of the 45Ca influx and 22Na efflux that were activated by physiological concentrations of intracellular free Ca2+, [Ca2+]i, were studied in internally perfused single giant barnacle muscle cells. Since both fluxes were activated by intracellular Ca2+ (Cai) and the Ca influx was dependent on internal Na+ (Nai), the fluxes appear to be coupled (Na/Ca exchange). Tracer Ca/Ca and Na/Na exchanges were eliminated by employing tris(hydroxymethyl)aminomethane (Tris) as the predominant external cation. Under these circumstances, the ratio of the external Ca2+ (Cao)-dependent, Cai-activated Na+ efflux to the Nai-dependent, Cai-activated Ca influx was 3.1-3.2 Na+/1 Ca2+, when the intracellular Na+ concentration, [Na+]i was either 30 or 46 mM. This is the first direct measurement of the Na/Ca exchange stoichiometry. In many types of cells, the Na/Ca exchange system appears to operate in parallel with a plasma membrane ATP-driven Ca pump that has a lower capacity (maximum velocity), but higher affinity for Ca2+ than the Na/Ca exchanger. The data on the stoichiometry and activation by internal Ca2+ imply that the turnover of the Na/Ca exchanger is modulated during periods of cell activity. When the cells are depolarized, the Na/Ca exchange system is activated by the rising [Ca2+]i, and Ca2+ entry via the exchanger is promoted. Then, at repolarization, Ca2+ exits rapidly, primarily via the exchanger. However, in resting cells, with a low [Ca2+]i, much (but not all) of the Ca2+ efflux is probably mediated by the ATP-driven Ca pump.
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Danaceau, Jonathan P., and Mary T. Lucero. "Electrogenic Na+/Ca2+ Exchange." Journal of General Physiology 115, no. 6 (June 1, 2000): 759–68. http://dx.doi.org/10.1085/jgp.115.6.759.

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Olfactory receptor neurons (ORNs) from the squid, Lolliguncula brevis, respond to the odors l-glutamate or dopamine with increases in internal Ca2+ concentrations ([Ca2+]i). To directly asses the effects of increasing [Ca2+]i in perforated-patched squid ORNs, we applied 10 mM caffeine to release Ca2+ from internal stores. We observed an inward current response to caffeine. Monovalent cation replacement of Na+ from the external bath solution completely and selectively inhibited the caffeine-induced response, and ruled out the possibility of a Ca2+-dependent nonselective cation current. The strict dependence on internal Ca2+ and external Na+ indicated that the inward current was due to an electrogenic Na+/Ca2+ exchanger. Block of the caffeine-induced current by an inhibitor of Na+/Ca2+ exchange (50–100 μM 2′,4′-dichlorobenzamil) and reversibility of the exchanger current, further confirmed its presence. We tested whether Na+/Ca2+ exchange contributed to odor responses by applying the aquatic odor l-glutamate in the presence and absence of 2′,4′-dichlorobenzamil. We found that electrogenic Na+/Ca2+ exchange was responsible for ∼26% of the total current associated with glutamate-induced odor responses. Although Na+/Ca2+ exchangers are known to be present in ORNs from numerous species, this is the first work to demonstrate amplifying contributions of the exchanger current to odor transduction.
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Blaustein, Mordecai P., and W. Jonathan Lederer. "Sodium/Calcium Exchange: Its Physiological Implications." Physiological Reviews 79, no. 3 (July 1, 1999): 763–854. http://dx.doi.org/10.1152/physrev.1999.79.3.763.

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The Na+/Ca2+exchanger, an ion transport protein, is expressed in the plasma membrane (PM) of virtually all animal cells. It extrudes Ca2+in parallel with the PM ATP-driven Ca2+pump. As a reversible transporter, it also mediates Ca2+entry in parallel with various ion channels. The energy for net Ca2+transport by the Na+/Ca2+exchanger and its direction depend on the Na+, Ca2+, and K+gradients across the PM, the membrane potential, and the transport stoichiometry. In most cells, three Na+are exchanged for one Ca2+. In vertebrate photoreceptors, some neurons, and certain other cells, K+is transported in the same direction as Ca2+, with a coupling ratio of four Na+to one Ca2+plus one K+. The exchanger kinetics are affected by nontransported Ca2+, Na+, protons, ATP, and diverse other modulators. Five genes that code for the exchangers have been identified in mammals: three in the Na+/Ca2+exchanger family ( NCX1, NCX2, and NCX3) and two in the Na+/Ca2+plus K+family ( NCKX1 and NCKX2). Genes homologous to NCX1 have been identified in frog, squid, lobster, and Drosophila. In mammals, alternatively spliced variants of NCX1 have been identified; dominant expression of these variants is cell type specific, which suggests that the variations are involved in targeting and/or functional differences. In cardiac myocytes, and probably other cell types, the exchanger serves a housekeeping role by maintaining a low intracellular Ca2+concentration; its possible role in cardiac excitation-contraction coupling is controversial. Cellular increases in Na+concentration lead to increases in Ca2+concentration mediated by the Na+/Ca2+exchanger; this is important in the therapeutic action of cardiotonic steroids like digitalis. Similarly, alterations of Na+and Ca2+apparently modulate basolateral K+conductance in some epithelia, signaling in some special sense organs (e.g., photoreceptors and olfactory receptors) and Ca2+-dependent secretion in neurons and in many secretory cells. The juxtaposition of PM and sarco(endo)plasmic reticulum membranes may permit the PM Na+/Ca2+exchanger to regulate sarco(endo)plasmic reticulum Ca2+stores and influence cellular Ca2+signaling.
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Dissertations / Theses on the topic "Na+/Ca2+ exchanger"

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Parnis, Julia [Verfasser]. "The physiological role of mitochondrial Na+/Ca2+ exchanger NCLX for glial Ca2+ homeostasis / Julia Parnis." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2013. http://d-nb.info/1031099506/34.

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Zhao, Jun, and e52677@ems rmit edu au. "The functional study of Na+/Ca2+ exchanger in vascular smooth muscle cells." RMIT University. Medical Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080617.163746.

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Na+/Ca2+ exchanger (NCX) is a membrane protein which can mediate either Ca2+ entry (reverse mode) or exit (forward mode) in cells. As one of the major Ca2+ transport systems, NCX is postulated to play a critical role in the vascular smooth muscle cell. The aims of the present study are to firstly demonstrate the functional existence of NCX in vascular smooth muscle (including aorta and arteriole); to clarify the modulation of NCX; to explore the selectivity of NCX inhibitor KB-R7943; and lastly to investigate the role of NCX in the myogenic response. KB-R7943 has been widely used as a NCX inhibitor. The study investigated its pharmacological actions in rat aorta on a variety of Ca2+ dependent systems. Rat aortic rings were used. The constriction to low extracellular [Na+] is a functional response mediated by NCX operating in reverse mode. The data demonstrate that 10 µM KB-R7943 inhibited L-type Ca2+ channel, the capacitative Ca2+ entry and  adrenergic receptor pathway. Nevertheless, KB-R7943 can be used as a selective inhibitor of NCX at the lower concentration of 1 µM in rat aortic rings. The study investigated whether the endothelium could modulate NCX in rat aortic rings. Lowering extracellular [Na+] to 1.18 mM induced constriction in endothelium denuded rat aortic rings, but only a small constriction in endothelium intact rat aortic rings. In endothelium intact rat aortic rings, the guanylate cyclise inhibitor ODQ (1 µM) and the nitric oxide synthase inhibitor L-NAME (50 µM) greatly amplified the vasoconstriction to lowering extracellular [Na+], but had no effect when the endothelium was removed. The adenylate cyclise inhibitor SQ 22536 (100 µM) and the cyclooxygenase inhibitor indomethacin (10 M) showed no significant effect on the low-Na+ induced vasoconstriction in either endothelium denuded or intact aortic rings. The results suggest that endothelium modulated the NCX operation via the nitric oxide/guanylate cyclase, not the adenylate cyclase system; further prostanoids including prostacyclin was not involved. The interaction between nitric oxide and NCX was furt her explored using the nitric oxide donor sodium nitroprusside. Endothelium denuded rat aortic rings were preconstricted to the same extent with either low Na+ (1.18 mM), or the thromboxane A2 agonist U46619 (0.1 µM) or high K+ (80 mM). The vasorelaxation of SNP (30 nM) in low Na+ constriction was significantly larger compared to other agents. This indicates that NO has a special antagonism of low Na+ constriction and a hypothesis is proposed involving Na+/K+ ATPase. The investigation of NCX is mainly conducted in large vessels; much less evidence is available for small resistance vessels. The study investigated the role of NCX on myogenic response in pressurized cremaster muscle arterioles. Reducing extracellular [Na+] resulted in graded vasoconstriction which was inhibited by NCX inhibitor SEA0400 (1 µM). Myogenic vasoconstriction and the concomitant rise in internal [Ca2+] were induced by a transmural pressure increase from 70 to 120 mmHg which was prevented by NCX inhibitor: SEA0400 (1 µM). In conclusion, the present study suggests that NCX contributes to the myogenic response in cremaster arteriole.
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PRITCHARD, TRACY J. "Expression and Function of the Na +-K +ATPase α-Isoforms in Smooth Muscle: Evidence from Transgenic Mice." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1186672962.

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Barman, Palash Pratim. "β-adrenoceptor/protein kinase A modulation of rabbit cardiac Na+-Ca2+ exchanger and cystic fibrosis transmembrane conductance regulator." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.617927.

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The Na2+-Ca2+ Exchanger (NCX), all important Ca2+ handling plasmalemmal protein, is expressed widely in cardiac tissues and plays important roles in physiological and pathophysiological cardiac function . A key aim of this study was to determine whether or not B-adrenoceptor/PKA stimulation modulates NCX current (lNCX), measured as Ni2+ sensitive current, independent of potential contamination from a PKA-activated CI current (lCIPKA), encoded by the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) channel. Pharmacological effects of a 'selective' CTFR blocker, GyH-101 were also tested. Additional work was also conducted on human atrial INCX and NCX expression. Methods: Rabbit ventricular and atrial and human atrial myocytes were used in whole-cell patch-clamp experiments at 37°C. Selective conditions for NCX and CI currents were used as appropriate. NCX protein was measured by Western Blotting. Results and conclusions: Under NCX•selective recording conditions 10 mM Ni2+ blocked isoprenaline activated current, but the Nil+• sensitive ventricular INcx activated by forskolin was similar to that in control. In rabbit atrial tissues, which lack ICLPKA, forskolin did not increase the Ni2-•sensitive current component. External but not internal Ni 21 inhibited lc1PKA, with a sub• millimolar IC50, when this was activated by isoprenaline but not forskolin suggestive of a Nil+ action upstream to adenylyl cyclase, likely directly on the B1• adrenoceptor. Thus, the apparent increase rabbit ventricular INt:x with isoprenaline in NCX recording conditions is likely to be attributable to overlapping Ni2+•sensitivc IctPKA, rather than INCX activation by B-adrenoceptor/PKA stimulation. The CFTR inhibitor GlyH•-1Ol produced voltage• dependent inhibition of cardiac IC1PKA, but additionally also inhibited I and IKI . Consequently this compound is not entirely CFTR•selective in respect of cardiac electrophysiology. Human atrial INt:x density and its current voltage relationship were very similar to those of rabbit atrial myocytes. In the human atrial samples examined, there was no significant difference in NCX protein expression between patients in sinus rhythm and those in chronic atrial fibrillation.
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Nakamura, Toshio. "Expression of the Na+/Ca2+ exchanger emerges in hepatic stellate cells after activation in association with liver fibrosis." Kyoto University, 1998. http://hdl.handle.net/2433/182267.

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Stabelini, Tatiana Comporte. "Estudos estruturais de fragmentos do trocador de Na+/Ca2+ por RMN em solução." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/46/46131/tde-11122018-091550/.

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Proteínas de membrana estão envolvidas em processos fisiológicos essenciais como, por exemplo, a manutenção do equilíbrio iônico e sinalização intracelular. No entanto, apesar do envolvimento em inúmeros processos fisiológicos e de grande interesse farmacêutico, o estudo estrutural de proteínas de membrana ainda é um processo custoso e muito mais complexo do que o estudo estrutural de proteínas solúveis. Os trocadores de Na+/Ca2+ são proteínas de membrana que atuam na manutenção da homeostase de Ca2+ intracelular e estão envolvidos em processos patológicos como doenças cardíacas. Estes trocadores estão presentes em diversas espécies de mamíferos (NCX) e insetos, por exemplo, na mosca Drosophila melanogaster (CALX). A topologia destas proteínas é constituída de dois domínios. O domínio transmembranar, que contém dois segmentos de 5 hélices transmembranares (TMH) e é responsável por promover o transporte específico de íons Ca2+ e Na+ através da membrana, e o domínio citoplasmático, responsável por regular a atividade do trocador. O domínio citoplasmático consiste de uma alça que contém dois domínios sensores de Ca2+ intracelular (CBD1 e CBD2). Trabalhos mostraram que o trocador CALX é inibido pela ligação de Ca em CBD1, enquanto que trocadores NCX são ativados. As regiões citosólicas que conectam CBD1 e CBD2 à TMH5 e TMH6 são conservadas e ainda não foram caracterizadas estruturalmente. Adjacente à TMH5 há um segmento anfipático, denominado exchanger inhibitory peptide (XIP), que está envolvido no mecanismo de regulação do trocador. Na ausência de dados estruturais do CALX completo, o estudo de TMH5-XIP poderá aumentar a compreensão sobre a estrutura e o funcionamento do trocador. A construção TMH5-XIP foi fusionada à MBP no N-terminal e a uma sequência de 8 histidinas no C-terminal. Apesar da expressão da proteína de fusão ter sido bem sucedida, problemas de precipitação e ineficiência durante a clivagem da conexão com a MBP impediram a conclusão dos estudos estruturais. Logo, uma construção menor, contendo apenas a região equivalente ao XIP, foi estudada por espectroscopia de RMN em solução e dicroísmo circular. XIP forma uma 310-hélice a baixa temperatura, 7 oC, que se desestabiliza a maior temperatura, 27 oC. Estes dados permitem a formulação de hipóteses sobre o papel de XIP no mecanismo de regulação do domínio transmembranar de CALX.
Membrane proteins are involved in essential physiological processes such as maintenance of the ionic balance and intracellular signaling. However, despite their role in numerous physiological processes of well-recognized pharmaceutical relevance, structural studies of membrane proteins remain being more complex than structural studies of globular proteins. Na+/Ca2+ exchangers (NCX) are membrane proteins that play essential roles in the maintenance of the intracellular Ca2+ homeostasis. Not surprisingly, the NCXs are involved in pathologies such as heart diseases. These exchangers are present in several species of mammals (NCX) and insects, for example, in the fly Drosophila melanogaster (CALX). The topology of these proteins consists of a transmembrane and a hydrophilic domain. The transmembrane domain corresponds to two segments of 5 transmembrane helices (TMH) forming a 10-helix bundle that is responsible for the specific transport of Ca2+ and Na+ across the cellular membrane. The hydrophilic domain is composed of a large cytoplasmic loop, which is associated with the regulation of the ion exchange activity of the transmembrane domain. The loop contains two Ca2+-sensors domains, CBD1 and CBD2, and uncharacterized regions. Studies showed that Ca2+ binding to CBD1 inhibits the CALX, whereas it activates the NCX. The juxtamembrane cytosolic regions linking the CBD1 and CBD2 domains to the TMH5 and TMH6, respectively, are highly conserved but have not yet been structurally characterized. The segment near TMH5 is amphipathic, and it is also called exchanger inhibitory peptide (XIP). In the absence of a three-dimensional structure of the complete CALX, the study of TMH5-XIP may contribute to our understanding of the structure and operation of the exchanger. In order to study TMH5-XIP, it was fused to an MBP tag at the N-terminus, and to a sequence of 8 histidines at the C-terminus. Although the expression of the fusion protein was successful, precipitation and inefficient MBP-tag cleavage prevented the isolation of pure TMH5-XIP for structural studies. Hence, a smaller construct, containing only the region equivalent to XIP, was studied by NMR spectroscopy in solution and circular dichroism. The structure assumed by XIP in solution is temperature dependent, being intrinsically disordered at 27 C or a 310-helix at 7 C, respectively. These findings allowed us to infer how XIP could participate in the CALX regulation mechanism.
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PICCIRILLO, SILVIA. "Involvement of Na+/Ca2+ Exchanger (NCX) in Glutamate-Induced Neuroprotection in SH-SY5Y Differentiated Cells Subjected to Hypoxia/Reoxygenation (H/R) Injury." Doctoral thesis, Università Politecnica delle Marche, 2019. http://hdl.handle.net/11566/263512.

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L’ischemia cerebrale è una patologia caratterizzata dalla ridotta o totale assenza di ossigeno e di substrati metabolici che influiscono sulla respirazione aerobia determinando un danno mitocondriale in particolare nella sintesi di ATP e nello squilibrio ionico culminando nella morte cellulare. L’entità del danno non deriva solo dall’insulto ischemico ma anche dai successivi fenomeni deleteri stimolati dal ripristino del flusso sanguigno e dei livelli di ossigeno. Lo squilibrio metabolico cerebrale induce l’utilizzo di fonti energetiche alternative come il glutammato. Sebbene in passato il glutammato è sempre stato considerato neurotossico, recenti studi hanno evidenziato come il glutammato possa svolgere il ruolo di intermediario metabolico stimolando la sintesi di ATP e migliorando l’attività mitocondriale, grazie al ruolo essenziale svolto dallo scambiatore Na+ /Ca2+ (NCX) e dai trasportatori del glutammato Na+ dipendenti (EAATs). In particolare, il ruolo solto da NCX nella neuroprotezione indotta da glutammato è stato studiato utilizzando un modello in vitro di ischemia cerebrale, cellule di neuroblastoma umano SH-SY5Y differenziate sottoposte ad ipossia/reossigenazione (H/R). In questo modello il danno indotto da H/R determina un aumento della mortalità cellulare, una riduzione dei livelli intracellulari di ATP e un’alterazione dei livelli di Ca2+ intracellulare. L’aggiunta di glutammato all’inizio della fase di reossigenazione determina un parziale recupero del danno inducendo un significativo aumento dei livelli di ATP. Inoltre, l’aggiunta di glutammato recupera parzialmente la riduzione dell’attività reverse-mode di NCX indotto da H/R. La trasfezione con i siRNA diretti contro NCX1 ed EAAT3 bloccano gli effetti protettivi del glutammato, confermando il ruolo essenziale svolto da NCX ed EAAT3 in questo pathway. In conclusione, i risultati ottenuti mostrano un nuovo ruolo svolto dal glutammato come “fattore di sopravvivenza” nel miglioramento del danno indotto da ipossia/reossigenazione, e che l’interazione tra NCX1 ed EAAT3 è fondamentale per permettere al glutammato di esplicare la sua funzione neuroprotettiva.
In brain ischemia, reduction of oxygen and substrates affects mitochondrial respiratory chain and aerobic metabolism culminating in ATP production impairment, ionic derangement and cell death. An exacerbation of the tissue damage frequently occurs during the restoration of blood flow and reoxygenation, giving rise to ischemia/reperfusion (I/R) injury. Energy dysfunction in cerebral metabolism may induce the utilization of alternative energy supplies, such as glutamate. Although glutamate has long been considered as a neurotoxin, it can also be used as a metabolic intermediate for the ATP synthesis thus improving mitochondrial activity. In this setting, both the Na+/Ca2+ exchanger (NCX) and the Na+ dependent Excitatory Amino Acid Transporters (EAATs) play a critical role. The aim of the present study is to investigate the role of NCX in the potential of glutamate to improve cell metabolism and survival of neuronal cells subjected to hypoxia/reoxygenation (H/R) injury. In SH-SY5Y neuroblastoma cells differentiated into neuron-like cells, H/R produced a significant cell damage, a drop of ATP cellular content and intracellular Ca2+ alterations. Exposure to glutamate at the onset of the reoxygenation phase induces an improvement of cell survival and a significant raise in intracellular ATP levels by stimulating mitochondrial oxidative phosphorylation. Furthermore, NCX reverse-mode is reduced in H/R cells and glutamate supplementation limits the H/R induced suppression of NCX activity. All the effects induced by glutamate exposure are lost when cells are transfected with small interfering RNA (siRNA) against NCX1 and EAAT3, suggesting that a functional interplay between these proteins is critically required for glutamate neuroprotection. Collectively, our results reveal the beneficial effect of glutamate in an in vitro model of H/R injury and focus on the essential role exerted by NCX1.
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Hammann, Jens [Verfasser]. "Influence of Na+, K+-ATPase and Na+/Ca2+ exchanger on developmental ion signaling and MBP synthesis in murine oligodendrocyte precursor cells / Jens Hammann." Mainz : Universitätsbibliothek Mainz, 2018. http://d-nb.info/1163416274/34.

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Al, Maghout Tamer [Verfasser]. "P38 Kinase, SGK1 and NF-κB Dependent Up-Regulation of Na+/Ca2+ Exchanger Expression and Activity Following TGFß1 Treatment of Megakaryocytes / Tamer Al Maghout." Tübingen : Universitätsbibliothek Tübingen, 2020. http://d-nb.info/1221596780/34.

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ALEMANNI, MATTEO. "The modulation of SERCA pump activity as a tool for management of hearth failure." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2009. http://hdl.handle.net/10281/7462.

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The current positive inotropic interventions for the management of heart failure (HF) are all associated to an unchanged or increased long term mortality, which limit their use. Istaroxime (IST) is a novel positive inotrope able to inhibit Na+, K+ ATPase and to stimulate SERCA pump. We employed IST as a tool to assess the role of a mild SERCA stimulation as a positive inotropic intervention. In a guinea pig model of HF, where the sarcoplasmic reticulum (SR) function was deranged, IST was able to restore an optimal SR function, increase the SR Ca2+ content and to improve all the EC coupling parameters considered. The comparison if IST and digoxin, a pure inhibitor of Na+, K+ ATPase, in mouse ventricular myocytes, showed that IST was less pro-arrhythmic than digoxin, as already observed in guinea pig. Digoxin induced a rapid accumulation of cytosolic Ca2+, while IST did not, and neither compound directly affected SR Ca2+ leakage, suggesting that a better compartmentalization of the ion was achieved in the presence of IST by the stimulation of SERCA pump. We concluded that the mild stimulation of SERCA is associated to a reduced pro-arrhythmic effect, and that it might represent a promising target for a new class of positive inotropic interventions associated to a reduced long term mortality.
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Books on the topic "Na+/Ca2+ exchanger"

1

Andre, Herchuelz, and New York Academy of Sciences, eds. Sodium-calcium exchange and the plasma membrane Ca2+-ATPase in cell function: Fifth international conference. Boston, Mass: Blackwell Pub. on behalf of the New York Academy of Sciences, 2007.

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Vries-Baayens, Anne Elisabeth. CAD product data exchange: Conversions for curves and surfaces. Delft, Netherlands: Delft University Press, 1991.

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Lanyi, Andrew A. Confessions of a stockbroker: You, too, can find tomorrow's blue chipsbefore Wall Street finds them. New York: Prentice Hall, 1992.

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Confessions of a stockbroker: You, too, can find tomorrow's blue chips before Wall Street finds them. New York: Prentice Hall, 1992.

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Smith, Brad Lee. Initial Graphics Exchange Specification (IGES), version 3.0. Warrendale, Pa: Society of Automotive Engineers, 1986.

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American Institute of Architects. Computer Aided Practice Task Force. CAD, the medium of exchange. Washington, DC (1735 New York Ave., NW, Washington 20006): American Institute of Architects, 1992.

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Helpenstein, Helmut J., ed. CAD Geometry Data Exchange Using STEP. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-78335-7.

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Chen, Yu-chin. Can exchange rates forecast commodity prices? Cambridge, MA: National Bureau of Economic Research, 2008.

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Jiabing, Chen, ed. Cai jing fan zui yu zheng quan jiao yi fa li lun·shi wu. Taibei Shi: Xin xue lin chu ban gu fen you xian gong si, 2009.

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Wai hui ye wu cao zuo yu feng xian guan li. Xiamen: Xiamen da xue chu ban she, 2003.

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Book chapters on the topic "Na+/Ca2+ exchanger"

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Clausen, Torben, José Luis Trejo, Mark P. Mattson, Alexis M. Stranahan, Joanna Erion, Rosa Maria Bruno, Stefano Taddei, and Melinda M. Manore. "Na+/Ca2+ Exchanger (NCX)." In Encyclopedia of Exercise Medicine in Health and Disease, 632. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-540-29807-6_2738.

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Harper, Alan G. S., and Stewart O. Sage. "TRP-Na+/Ca2+ Exchanger Coupling." In Advances in Experimental Medicine and Biology, 67–85. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-26974-0_4.

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Philipson, Kenneth D. "The Na+-Ca2+ exchanger: Molecular aspects." In Developments in Cardiovascular Medicine, 435–45. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-011-3990-8_38.

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Shoshan-Barmatz, Varda, and Soumasree De. "Mitochondrial VDAC, the Na+/Ca2+ Exchanger, and the Ca2+ Uniporter in Ca2+ Dynamics and Signaling." In Advances in Experimental Medicine and Biology, 323–47. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-55858-5_13.

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Jalloul, Ali H., Robert T. Szerencsei, Tatiana P. Rogasevskaia, and Paul P. M. Schnetkamp. "SLC24A Family (K+-Dependent Na+-Ca2+ Exchanger, NCKX)." In Encyclopedia of Signaling Molecules, 4994–5002. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-67199-4_101860.

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Jalloul, Ali H., Robert T. Szerencsei, Tatiana P. Rogasevskaia, and Paul P. M. Schnetkamp. "SLC24A Family (K+-Dependent Na+-Ca2+ Exchanger, NCKX)." In Encyclopedia of Signaling Molecules, 1–9. New York, NY: Springer New York, 2017. http://dx.doi.org/10.1007/978-1-4614-6438-9_101860-1.

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Altimimi, Haider F., Robert T. Szerencsei, and Paul P. M. Schnetkamp. "Functional and Structural Properties of the NCKX2 Na+-Ca2+/K+ Exchanger: A Comparison with the NCX1 Na+/Ca2+ Exchanger." In Advances in Experimental Medicine and Biology, 81–94. Boston, MA: Springer US, 2012. http://dx.doi.org/10.1007/978-1-4614-4756-6_8.

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Hilge, Mark. "Ca2+ Regulation in the Na+/Ca2+ Exchanger Features a Dual Electrostatic Switch Mechanism." In Advances in Experimental Medicine and Biology, 27–33. Boston, MA: Springer US, 2012. http://dx.doi.org/10.1007/978-1-4614-4756-6_3.

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Zheng, Lei, Mousheng Wu, and Shuilong Tong. "Structural Studies of the Ca2+ Regulatory Domain of Drosophila Na+/Ca2+ Exchanger CALX." In Advances in Experimental Medicine and Biology, 55–63. Boston, MA: Springer US, 2012. http://dx.doi.org/10.1007/978-1-4614-4756-6_6.

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Ballard-Croft, Cherry, and Stephen Schaffer. "Stimulatlon of the Na+/Ca2+ Exchanger by Angiotensin II." In Progress in Experimental Cardiology, 395–402. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-5743-2_29.

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Conference papers on the topic "Na+/Ca2+ exchanger"

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Dong, H., J. Chow, C. Estrema, M. Ban, C. Kytasty, and TD Bigby. "Na+/Ca2+Exchanger as a Potential Target of Asthma Therapy." In American Thoracic Society 2009 International Conference, May 15-20, 2009 • San Diego, California. American Thoracic Society, 2009. http://dx.doi.org/10.1164/ajrccm-conference.2009.179.1_meetingabstracts.a5605.

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Montaño, Luis M., Edgar Flores-Soto, Jorge Reyes García, Verónica Carbajal, and Carlos Barajas López. "ATP Promotes The Reverse Mode Of The Na+/Ca2+ Exchanger Through P2X Receptors: Possible Role In The Refilling Of The Sarcoplasmic Reticulum In The Guinea Pig Airway Smooth Muscle." In American Thoracic Society 2010 International Conference, May 14-19, 2010 • New Orleans. American Thoracic Society, 2010. http://dx.doi.org/10.1164/ajrccm-conference.2010.181.1_meetingabstracts.a2130.

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Stokes, Harlan. "IGES Success on a Shoestring: A Management Case Study of CAD/CAM Data Exchange." In ASME 1991 International Computers in Engineering Conference and Exposition. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/cie1991-0043.

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Abstract In the Autumn of 1988, the Materials Operations at Control Data Corporation’s Computer Products Group began a program to electronically exchange mechanical CAD models with its suppliers. The “Supplier CAD-Link” program provided many immediate benefits and offers a unique learning experience about electronic data interchange. Existing technologies are used, so the program operates on a shoestring budget with no major dollar investments required of CDC or the suppliers. The program uses the IGES standard file format, so suppliers can apply the lessons learned to CAD/CAM data exchanges with other companies. Now, with the continuing success of the CAD-Link program. Computer Products is re-evaluating many of the old paper based methods of doing business. This paper explores some of the issues for managing a CAD/GAM data exchange program.
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Ito, Takamasa, Jinliang Yuan, and Bengt Sunde´n. "Analysis of Intercooler in PEM Fuel Cell Systems." In ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ht-fed2004-56587.

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Heat exchangers are used in proton exchange membrane fuel cell systems (PEMFCs) for stack cooling, intercooling, water condensation and fuel reforming. Especially, the heat exchanger for the intercooling before the humidifier is investigated in this paper. It is found that, at high pressure or high mass flow rate, the need to cool the air (oxidant) is large. The heat exchanger uses coolant water from the stack cooling system or ambient air as the cold stream. With water-cooling, the volume of the heat exchanger will be small. However, difficulties exist because the small available temperature difference. Air-cooling can be used over a wide operating range but the heat exchanger volume will be large.
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Wise, Timothy D. "Interface of optical design programs to CAD/CAE/CAM software." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.tuk3.

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CAD/CAM systems permit the manufacture of real physical parts on a milling, or other shop, machine which has received its instructions from the design system. However, a persistent problem has been the lack of a link between the optical CAD software and mechanical CAD software. A past paper described software which bridges this gap by producing an International Graphics Exchange Standard (IGES) file from the neutral plot files of the optical model. This IGES file can then be directly read into the mechanical drafting and design programs, ANVIL and GEOMOD. Although the latest enhancements to this older interface are addressed, the main thrust is the description of three completely new capabilities: (1) the ability to read directly NASTRAN-generated strain data for optical surfaces into the optical design program CODE-V, (2) the direct passage of a standard lens prescription in CODE-V to the program APART for stray light analysis, and (3) the entry of mechanical drafting data directly into APART via IGES files. This last interface is particularly exciting because it allows, for the first time, a completely graphic entry of structural data into an optical analysis program. A description of the typical procedures used to accomplish the transfer of data is provided along with several examples. Plans are presented to use these new software links to achieve paperless manufacture of optomechanical systems. Since the current algorithms have been designed with an eye on eventual improvements, an assessment of current limitations and future enhancements is also included.
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Ye, Peng, Yonggang Zhang, Yanglan Wang, Geying Huang, and Lianshui Guo. "A Method of Parametric Model Data Exchange and Reconstruction Based on Feature Script." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-69067.

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Abstract In collaborative product development (CPD), iterative design with heterogeneous CAD systems is always completed by original equipment manufacturers (OEMs) and other suppliers around the world. Therefore, product data exchanges among different heterogeneous CAD systems are crucial in CPD. However, the major bottleneck is that parametric part models of complex products cannot be exchanged among heterogeneous CAD systems. Published by the International Organization for Standardization (ISO), the Standard for the Exchange of Product Model Data (STEP) is the most common solution for geometry-based data exchanges and product annotations in the manufacturing industry. However, the exchanged STEP parts cannot be modified due to the loss of important information including modeling history, parameters and constraints, which involve the design intent. Therefore, the challenge of modification on exchanged parts needs to be overcome for iterative design in heterogeneous CAD systems of the manufacturing industry. In this paper, a method of part parametric model data exchange and reconstruction based on feature script is proposed. The main idea is features, which include reference features (like datum-plane, datum-axis, and datum-point), shape features (like extrude and rotation), auxiliary features (like fillet and chamfer), and sketch features. These features are taken as the fundamental elements of a part in CAD system, and each is defined by feature script and saved as an extensible markup language (XML) node. The feature modeling history of a part is regarded as a tree structure, which can be converted to an XML tree structure. In part model reconstruction, the proposed method utilizes a persistent naming mechanism and geometric data to identify topological entities, and then realize the persistence of constraint information and parameter driving of part model. The proposed method will be applied to part data exchange and parametric model reconstruction among heterogeneous CAD systems in the following process: (i) the feature tree and parameters of the parametric model are obtained in the source CAD system; (ii) the feature model data is translated into feature script and saved as XML format file; (iii) the feature script file is read, and the parametric model is reconstructed in the target CAD system according to modeling history. In order to verify the accuracy of data exchange and model reconstruction between Creo and CATIA, a method on constraints equivalence analysis and feature comparison is also proposed for analyzing the similarities and differences between source and target parametric models. In addition, a case study is presented to demonstrate the potentials of the proposed method for parametric-feature model exchanges among heterogeneous CAD systems in web-based collaborative product development.
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Rivera-Hernandex, Yaixa L., and Timothy A. Shedd. "High-Performance Impingement-Based Ultracompact Heat Exchanger." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43837.

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Significant advances have been made in compact liquid-liquid heat exchangers in the recent past, such as the brazed plate heat exchanger with enhanced plate geometries. However, additional improvements in heat exchanger performance may be realized by incorporating impinging jet flow rather than flow parallel to the heat exchange surface. It has been recognized for some time that highly efficient heat transfer over large areas can be attained using impinging jets with nearby drains, but no design model is available for this configuration. This paper presents a relatively simple theory for the heat transfer performance of jet-drain arrays based on the concept of transient heat transfer to the liquid. This theory is verified by comparison to experimental data. Next, the design and implementation of a liquid-liquid heat exchanger based on jet-drain arrays is presented and the performance of this novel device is directly compared with that of a brazed-plate heat exchanger. In addition, computational fluid dynamics simulations are used to design an enhanced impingement plate that virtually eliminates interactions between neighboring jets, further improving performance. Using the theory developed in this paper, very high performance compact liquid-liquid heat exchangers can be designed with relatively large orifices (approx. 1 mm), allowing for low pressure loss and the ability to pass a significant amount of solids through without clogging.
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Cruickshank, Cynthia A., and Stephen J. Harrison. "Experimental Characterization of a Natural Convection Heat Exchanger for Solar Domestic Hot Water Systems." In ASME 2006 International Solar Energy Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/isec2006-99130.

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To predict the long-term performance of solar domestic hot water (SDHW) systems requires computational models that can characterize the systems under a range of operating conditions. The development of detailed fundamental models that suitably describe the operation of systems with natural convection heat exchangers is, however, difficult and time consuming. The fact that the natural convection flow through the heat exchanger is intrinsically self-controlling and temperature dependent complicates the analysis. One approach to modeling this type of system is to use performance characteristics, empirically derived from experimental data, to predict the performance of the heat exchanger under typical operating conditions. Unfortunately, a significant number of tests may be required to characterize the full operation of the device. This paper presents a simplified test method that was developed to allow pre-configured SDHW systems that use natural convection heat exchangers, to be characterized. The results of this test method produce performance coefficients for simple empirical expressions that describe the fluid flow and heat transfer in the heat-exchange loop. These empirically derived coefficients are an input to a general simulation routine that allows overall system performance to be determined for various loads and climatic conditions. In this paper, data is presented for a typical heat exchanger under a range of operational conditions.
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Yoon, Seok Ho, Dong-Wook Oh, Young Kim, and Jun Seok Choi. "Experimental Study on the Heat Transfer Performance of the Diffusion-Bonded Micro Channel Heat Exchanger in the Pilot-Scale Test Facility." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63426.

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The heat exchangers using micro channel structure have been studied due to its high efficiency and compactness. If the micro channel heat exchanger is applied to the natural gas liquefaction process, the efficiency of LNG plant can be improved. In this study, the micro channel was fabricated by chemical etching and the heat exchanger core was made by the diffusion bonding method for cryogenic reliability. For applying to the large scale plant such as LNG plant, the pilot-scale thermal performance test setup of the heat exchanger was built. Tests can be performed in the cryogenic environment. The working fluid is cryogenic nitrogen gas. Two different temperature level of nitrogen gas was made by vaporizing from liquid nitrogen. And these fluids exchange the heat through the micro channel heat exchanger. Test rig is an open loop. Therefore nitrogen gas is discharged to the ambient. Temperatures are measured by RTD sensors. Inlet pressures of heat exchanger are measured by the cryogenic pressure transducer and pressure differences of heat exchanger are measured by the differential pressure transmitters. And all the measured data is acquired by DAQ module and saved into PC. The heat transfer coefficients of the micro channel heat exchanger are calculated and the heat transfer characteristics are investigated. And the test result was compared with the existing heat transfer correlations. And the modified heat transfer correlation of the micro channel heat exchanger in the cryogenic environment is suggested.
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Ding, Ju, Min Zhang, Shuhong Liu, Shenghui Wang, and Jielu Wang. "Inspection Method of Finned Tube and Finned Heat Exchanger." In ASME 2021 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/pvp2021-60907.

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Abstract The finned tube heat exchanger is one of the earliest and most successful discoveries in the process of improving tube heat exchange. This method is still the most widely used of all kinds of tube heat transfer surface enhancement heat transfer methods. It is not only suitable for single-fin tube heat exchangers, which are widely used in power, chemical, petrochemical, air-conditioning engineering and refrigeration engineering. Conventional heat exchanger with smooth tubes can be inspected through the pressure test during the manufacturing process. Finned tubes and finned heat exchangers with inner thread structure have some difficult to pass the water pressure test. The same situation exists in regular inspections. Due to structural reasons, it is difficult to carry out regular surface inspections[1]. For these two situations, two different testing methods are required to ensure quality. This article introduces in detail the methods of inspecting finned tubes and finned heat exchangers. Hierarchical comparison of alternatives in hydrostatic testing project, and the eddy current detection technology of the finned tube under the condition of in-service air cooling. The far-field eddy current method is chosen for inspection. And by comparing the standard sample tube, it is mainly used to adjust the sensitivity of the eddy current detector and ensure the accuracy of the test results[2]. The results show that the eddy current detection technology can be more accurate and reliable. The corrosion of the finned tube under service air cooling is detected, and a reliable basis is provided for judging the use of the finned tube and finned heat exchanger[3].
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Reports on the topic "Na+/Ca2+ exchanger"

1

Avnimelech, Yoram, Richard C. Stehouwer, and Jon Chorover. Use of Composted Waste Materials for Enhanced Ca Migration and Exchange in Sodic Soils and Acidic Minespoils. United States Department of Agriculture, June 2001. http://dx.doi.org/10.32747/2001.7575291.bard.

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Restoration of degraded lands and the development of beneficial uses for waste products are important challenges facing our society. In addition there is a need to find useful and environmentally friendly applications for the organic fractions of municipal and other solid waste. Recent studies have shown that composted wastes combined with gypsum or gypsum-containing flue gas desulfurization by-products enhance restoration of sodic soils and acidic minespoils. The mechanism by which this synergistic effect occurs in systems at opposite pH extremes appears to involve enhanced Ca migration and exchange. Our original research objectives were to (1) identify and quantify the active compost components involved in Ca transport, (2) determine the relative affinity of the compost components for Ca and competing metals in the two soil/spoil systems, (3) determine the efficacy of the compost components in Ca transport to subjacent soil and subsequent exchange with native soil cations, and (4) assess the impacts of compost enhanced Ca transport on soil properties and plant growth. Acidic mine spoils: During the course of the project the focus for objective (1) and (2) shifted more towards developing and evaluating methods to appropriately quantify Ca2+ and Al3+ binding to compost derived dissolved organic matter (DOM). It could be shown that calcium complexation by sewage sludge compost derived DOM did not significantly change during the composting process. A method for studying Al3+ binding to DOM was successfully developed and should allow future insight into DOM-Al3+ interactions in general. Laboratory column experiments as well as greenhouse experiments showed that in very acidic mine spoil material mineral dissolution controls solution Al3+ concentration as opposed to exchange with Ca2+. Therefore compost appeared to have no effect on Al3+ and Ca2+ mobility and did not affect subsoil acidity. Sodic alkaline soils: Batch experiments with Na+ saturated cation exchange resins as a model for sodic soils showed that compost home cations exchanged readily with Na+. Unlike filtered compost extracts, unfiltered compost suspensions also significantly increased Ca2+ release from CaCO3. Soil lysimeter experiments demonstrated a clear impact of compost on structural improvement in sodic alkaline soils. Young compost had faster, clearer and longer lasting effects on soil physical and chemical properties than mature compost. Even after 2 growing seasons differences could still be observed. Compost increased Ca2+ concentration in soil solution and solubility of pedogenic CaCO3 that is highly insoluble under alkaline conditions. The solubilized Ca2+ efficiently exchanged Na+ in the compost treated soils and thus greatly improved the soil structure.
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2

Ferraro, Domenico, Kenneth Rogoff, and Barbara Rossi. Can Oil Prices Forecast Exchange Rates? Cambridge, MA: National Bureau of Economic Research, April 2012. http://dx.doi.org/10.3386/w17998.

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3

Chen, Yu-Chin, Kenneth Rogoff, and Barbara Rossi. Can Exchange Rates Forecast Commodity Prices? Cambridge, MA: National Bureau of Economic Research, March 2008. http://dx.doi.org/10.3386/w13901.

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4

Blanchard, Olivier, Gustavo Adler, and Irineu de Carvalho Filho. Can Foreign Exchange Intervention Stem Exchange Rate Pressures from Global Capital Flow Shocks? Cambridge, MA: National Bureau of Economic Research, July 2015. http://dx.doi.org/10.3386/w21427.

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5

Davis, K. J., S. J. Richardson, and N. L. Miles. Regional Ecosystem-Atmosphere CO2 Exchange Via Atmospheric Budgets. Office of Scientific and Technical Information (OSTI), March 2007. http://dx.doi.org/10.2172/900475.

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6

Engel, Charles. Can the Markov Switching Model Forecast Exchange Rates? Cambridge, MA: National Bureau of Economic Research, November 1992. http://dx.doi.org/10.3386/w4210.

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7

Lewis, Karen, and Edith Liu. How Can Asset Prices Value Exchange Rate Wedges? Cambridge, MA: National Bureau of Economic Research, September 2022. http://dx.doi.org/10.3386/w30422.

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8

Anderson, Mark, Greg Nellis, and Michael Corradini. Materials, Turbomachinery and Heat Exchangers for Supercritical CO2 Systems. Office of Scientific and Technical Information (OSTI), October 2012. http://dx.doi.org/10.2172/1053848.

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9

Neely, Christopher J., and Michael J. Dueker. Can Markov Switching Models Predict Excess Foreign Exchange Returns? Federal Reserve Bank of St. Louis, 2001. http://dx.doi.org/10.20955/wp.2001.021.

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10

van Wincoop, Eric, and Philippe Bacchetta. Can Information Heterogeneity Explain the Exchange Rate Determination Puzzle? Cambridge, MA: National Bureau of Economic Research, February 2003. http://dx.doi.org/10.3386/w9498.

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