Journal articles on the topic 'Frogs – Physiology'
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1
Smotherman, M. S., and P. M. Narins. "Hair cells, hearing and hopping: a field guide to hair cell physiology in the frog." Journal of Experimental Biology 203, no. 15 (August 1, 2000): 2237–46. http://dx.doi.org/10.1242/jeb.203.15.2237.
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For more than four decades, hearing in frogs has been an important source of information for those interested in auditory neuroscience, neuroethology and the evolution of hearing. Individual features of the frog auditory system can be found represented in one or many of the other vertebrate classes, but collectively the frog inner ear represents a cornucopia of evolutionary experiments in acoustic signal processing. The mechano-sensitive hair cell, as the focal point of transduction, figures critically in the encoding of acoustic information in the afferent auditory nerve. In this review, we provide a short description of how auditory signals are encoded by the specialized anatomy and physiology of the frog inner ear and examine the role of hair cell physiology and its influence on the encoding of sound in the frog auditory nerve. We hope to demonstrate that acoustic signal processing in frogs may offer insights into the evolution and biology of hearing not only in amphibians but also in reptiles, birds and mammals, including man.
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McCAY, MICHAEL G. "AERODYNAMIC STABILITY AND MANEUVERABILITY OF THE GLIDING FROG POLYPEDATES DENNYSI." Journal of Experimental Biology 204, no. 16 (August 15, 2001): 2817–26. http://dx.doi.org/10.1242/jeb.204.16.2817.
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SUMMARY Gliding has evolved independently in two families of tree frog. Tree frogs glide to descend rapidly to mating sites over temporary pools on the forest floor or to escape predators. The physical mechanisms used by frogs to glide and maneuver were investigated using a combination of observations of live frogs (Polypedates dennysi) gliding in a tilted wind-tunnel and aerodynamic forces and torques measured from physical models of tree frogs in a wind-tunnel. Tree frogs maneuvered in the tilted wind-tunnel using two different turning mechanisms: a banked turn (the frog rolls into the turn) and a crabbed turn (the frog yaws into the turn). Polypedates dennysipossessed overall weak aerodynamic stability: slightly stable about the pitch and roll axis, slightly unstable about the yaw axis. The maneuverability of gliding tree frogs was quantified using a maneuverability index. The maneuverability of tree frogs was roughly equivalent for tree frogs performing a banked turn and performing a crabbed turn. The maneuverability of tree frogs was approximately one-third of the maneuverability of a falcon (Falcon jugger).
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Shirokova, N., J. García, G. Pizarro, and E. Ríos. "Ca2+ release from the sarcoplasmic reticulum compared in amphibian and mammalian skeletal muscle." Journal of General Physiology 107, no. 1 (January 1, 1996): 1–18. http://dx.doi.org/10.1085/jgp.107.1.1.
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Puzzled by recent reports of differences in specific ligand binding to muscle Ca2+ channels, we quantitatively compared the flux of Ca2+ release from the sarcoplasmic reticulum (SR) in skeletal muscle fibers of an amphibian (frog) and a mammal (rat), voltage clamped in a double Vaseline gap chamber. The determinations of release flux were carried out by the "removal" method and by measuring the rate of Ca2+ binding to dyes in large excess over other Ca2+ buffers. To have a more meaningful comparison, the effects of stretching the fibers, of rapid changes in temperature, and of changes in the Ca2+ content of the SR were studied in both species. In both frogs and rats, the release flux had an early peak followed by fast relaxation to a lower sustained release. The peak and steady values of release flux, Rp and Rs, were influenced little by stretching. Rp in frogs was 31 mM/s (SEM = 4, n = 24) and in rats 7 +/- 2 mM/s (n = 12). Rs was 9 +/- 1 and 3 +/- 0.7 mM/s in frogs and rats, respectively. Transverse (T) tubule area, estimated from capacitance measurements and normalized to fiber volume, was greater in rats (0.61 +/- 0.04 microns-1) than in frogs (0.48 +/- 0.04 micron-1), as expected from the greater density of T tubuli. Total Ca in the SR was estimated as 3.4 +/- 0.6 and 1.9 +/- 0.3 mmol/liter myoplasmic water in frogs and rats. With the above figures, the steady release flux per unit area of T tubule was found to be fourfold greater in the frog, and the steady permeability of the junctional SR was about threefold greater. The ratio Rp/Rs was approximately 2 in rats at all voltages, whereas it was greater and steeply voltage dependent in frogs, going through a maximum of 6 at -40 mV, then decaying to approximately 3.5 at high voltage. Both Rp and Rs depended strongly on the temperature, but their ratio, and its voltage dependence, did not. Assuming that the peak of Ca2+ release is contributed by release channels not in contact with voltage sensors, or not under their direct control, the greater ratio in frogs may correspond to the relative excess of Ca2+ release channels over voltage sensors apparent in binding measurements. From the marked differences in voltage dependence of the ratio, as well as consideration of Ca(2+)-induced release models, we derive indications of fundamental differences in control mechanisms between mammalian and amphibian muscle.
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Maekawa, Shun, Hitomi Iemura, Yuko Kuramochi, Nami Kosaka-Nogawa, Hironori Nishikawa, Youichi Aizawa, and Takashi Kato. "A New Animal Model for Anemia Induced by Environmental Low-Temperature: Physiology of Erythrocyte Production and Circulation." Blood 112, no. 11 (November 16, 2008): 4770. http://dx.doi.org/10.1182/blood.v112.11.4770.4770.
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Abstract To survive, organisms must adapt to changes in the ambient environment. Here, we describe a new model of anemia based on exposure of African clawed frog, Xenopus laevis to low-temperature. Frogs exposed at low-temperature (5ºC) for five days had decreased numbers of peripheral blood erythrocytes, leukocytes, and thrombocytes as well as low hemoglobin levels. By contrast, spleen erythrocytes increased in number. Cell counts returned to normal in frogs re-warmed at ambient temperature (22ºC) for two days. To confirm these observations in vivo, we labeled peripheral blood cells with fluorescent reagent CFSE. During five days at 5ºC, labeled erythrocytes in peripheral blood decreased in number while those in spleen increased. When the temperature was raised to 22ºC, however, their numbers increased in peripheral blood. The findings suggested that exposure to low-temperature resulted in splenic pooling of peripheral erythrocytes. Accordingly, we looked at recovery from anemia induced by phenylhydrazine (PHZ) in this model. PHZ-treated frogs maintained at 22ºC decreased numbers of peripheral erythrocytes that were minimal on day 8, and increased gradually thereafter. In the liver, we found erythrocyte progenitors expressing erythropoietin receptor and GATA1-A detected by reverse transcription polymerase chain reactions and immunocytochemical staining but no mature forms. In PHZ-treated frogs exposed to 5ºC, peripheral erythrocyte counts remained minimal from day 8, and reversibly recovered when temperature returned to 22ºC. Erythrocyte progenitors were present in liver on day 8 but absent on day 12. Conversely, mature erythrocytes were absent in liver on day 8 but present on day 12. Finally, to learn whether the progenitors proliferate and differentiate without migrating from liver to peripheral blood, we treated frogs with thymidine analog bromodeoxyuridine (BrdU). In frogs kept at 22 ºC, BrdU-labeled erythrocytes were abundant in both liver and peripheral blood. However, frogs cooled at 5ºC had labeled cells in liver but few in peripheral blood. The findings suggest low-temperature exposure cause this anemia by impairing migration of mature/immature erythrocytes from the liver. In summary, this amphibian model offers a new perspective for investigating physiological effects of environmental temperature on vertebrate erythropoiesis.
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Layne, J. R., R. E. Lee, and T. L. Heil. "Freezing-induced changes in the heart rate of wood frogs (Rana sylvatica)." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 257, no. 5 (November 1, 1989): R1046—R1049. http://dx.doi.org/10.1152/ajpregu.1989.257.5.r1046.
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During the first few hours of freezing the cardiovascular system must distribute cryoprotectant throughout the body of freeze-tolerant frogs. This study presents initial documentation of the changes in heart rate of wood frogs (Rana sylvatica) during nonlethal freezing. Heart rate was determined by measuring the electrocardiogram of frogs. Within 1 min of the onset of freezing the heart rate nearly doubled to approximately 8.0 beats/min. The heart rate began to slow after the first hour of the freeze, and the heart completely stopped beating near the completion of ice formation approximately 20 h later. Recordings from a single frog revealed that the heart beat resumes within 1 h after thawing and near-normal function is achieved after only a few hours. The release of the latent heat of fusion caused a rise in body temperature (1.7 degrees C) for a few hours and was closely correlated with an increase in the heart rate. However, other factors such as reduction in blood volume, increase in blood viscosity, and progressive hypoxia may prominently influence cardiac function indirectly. Regardless, the heart functions long enough to distribute glucose throughout the body during the first few hours of the freeze.
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Klop-Toker, Kaya L., Jose W. Valdez, Michelle P. Stockwell, Matthew E. Edgar, Loren Fardell, Simon Clulow, John Clulow, and Michael J. Mahony. "Assessing host response to disease treatment: how chytrid-susceptible frogs react to increased water salinity." Wildlife Research 44, no. 8 (2017): 648. http://dx.doi.org/10.1071/wr16145.
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Context The severity and prevalence of the amphibian fungal pathogen, Batrachochytrium dendrobatidis (Bd) is correlated with several environmental variables, including salinity, temperature, and moisture content, which influence the pathogen’s growth and survival. Habitats that contain these environmental variables at levels outside of those optimal for Bd growth and survival may facilitate the survival of susceptible host species. Therefore, manipulation of environmental salinity is a potential management strategy to help conserve Bd-susceptible species. However, host behaviour also influences disease dynamics, and the success of habitat manipulation programs depends on how hosts use this altered habitat. Aims To assess if the Bd-susceptible green and golden bell frog, Litoria aurea, will select waterbodies with a salinity increased to S=3; if this selection is affected by infection; and if a frog’s time in a waterbody of this salinity affects infection load or blood physiology. Methods We conducted a filmed choice experiment and a 3-year field study where infected and uninfected frogs could choose between fresh or saline waterbodies. Key results In both the laboratory experiment and field study, Bd-infected L. aurea spent a significantly greater amount of time in or closer to a waterbody than uninfected frogs. Experimentally infected frogs tended to prefer the saline water over fresh, but their choice of water usage did not differ statistically from uninfected frogs. In the field, frogs began to avoid ponds when salinities rose above S=5. Conclusions Because both wild and captive, and infected and uninfected L. aurea readily selected waterbodies with a salinity of S=3, this salinity could potentially be used as a passive method for reducing the severity of Bd when managing this species. However, further testing is needed to understand the efficacy of this treatment, and care must be taken to prevent salinities rising above S=5, because this level seems to produce an avoidance response and therefore may not be suitable in every location. Implications Manipulation of aquatic habitats may be a worthwhile focus for Bd management in habitats where water level fluctuations are minimal.
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Baker, B. J., and J. M. L. Richardson. "The effect of artificial light on male breeding-season behaviour in green frogs, Rana clamitans melanota." Canadian Journal of Zoology 84, no. 10 (October 2006): 1528–32. http://dx.doi.org/10.1139/z06-142.
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Artificial night lighting (or ecological light pollution) is only now gaining attention as a source of long-term effects on the ecology of both diurnal and nocturnal animals. The limited data available clearly indicate that artificial light can affect physiology and behaviour of animals, leading to ecological consequences at the population, community, and ecosystem levels. Aquatic ecosystems may be particularly vulnerable to such effects, and nocturnally breeding animals such as frogs may be especially affected. To address this potential, we quantify the effects of artificial light on calling and movement behaviour in a rural population of male green frogs ( Rana clamitans melanota (Rafinesque, 1820)) during the breeding season. When exposed to artificial light, frogs produced fewer advertisement calls and moved more frequently than under ambient light conditions. Results clearly demonstrate that male green frog behaviour is affected by the presence of artificial light in a manner that has the potential to reduce recruitment rates and thus affect population dynamics.
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Rubin, Bruce K., Chris I. Cheeseman, Sita Gourishankar, and Malcolm King. "Is there a seasonal variation in mucus transport and nutrient absorption in the leopard frog?" Canadian Journal of Physiology and Pharmacology 70, no. 4 (April 1, 1992): 442–46. http://dx.doi.org/10.1139/y92-056.
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We postulated that as a hibernating species, frogs might have variable demands for nutrients at different seasons of the year and that this must be reflected in seasonal variations of physiologic processes related to nutrient transport and absorption. We examined the rate of mucus transport on the ciliated palate and the movement of nutrients across the intestinal lumen of leopard frogs, Rana pipiens. Mucus transport on the frog palate was strongly influenced by season, with maximal transport occurring in late June (Julian day 178, p = 0.0001; r = 0.58). This increased transport rate was associated with a summertime increase in mucus recoil (lower tangent δ) and a decrease in mucus hydration (increase in percent solids composition). Intestinal transport of leucine, lysine, and galactose did not appear to exhibit seasonal variability. These data suggest that different mechanisms may operate in determining seasonal variability in physiologic responses.Key words: mucociliary clearance, mucus viscoelasticity, intestinal absorption, Anura, seasonal variation.
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Alonso-Gómez, A. L., M. Tejera, M. Alonso-Bedate, and M. J. Delgado. "Response to pinealectomy and blinding in vitellogenic female frogs (Rana perezi) subjected to high temperature in autumn." Canadian Journal of Physiology and Pharmacology 68, no. 1 (January 1, 1990): 94–98. http://dx.doi.org/10.1139/y90-014.
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The present experiments were carried out to investigate the effects of pinealectomy and bilateral enucleation on the ovarian activity in Rana perezi frogs maintained in 12-h light – 12-h dark photoperiod and 20 ± 1 °C during the vitellogenetic growth in late autumn. These environmental conditions, mainly temperature, induce a gonadal and metabolic response similar to that observed in the natural habitat in summer: a marked ovarian follicular regression, a depletion of the energetic resources from fat bodies and liver, and a minimum in oestradiol circulating levels. This response is partially blocked by pinealectomy and blinding. Protein phosphorus, as an index of vitellogenic proteins, and total ovary lipid content were significantly higher in pinealectomized and blinded frogs with respect to sham-operated animals. Likewise, oestradiol concentrations showed a significant increase during the dark phase of the daily photocycle in pinealectomized and blinded animals. From our results, we can suggest that the arrest of vitellogenesis, the depletion of energetic resources, and the regulation of oestradiol levels induced by the high temperature in Rana perezi frogs can be influenced, at least in part, by the pineal complex and lateral eyes.Key words: pinealectomy, blinding, vitellogenesis, frog, temperature.
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Medler, Scott. "Anesthetic MS-222 eliminates nerve and muscle activity in frogs used for physiology teaching laboratories." Advances in Physiology Education 43, no. 1 (March 1, 2019): 69–75. http://dx.doi.org/10.1152/advan.00114.2018.
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Frogs are routinely used in physiology teaching laboratories to demonstrate important physiological processes. There have been recent directives that promote the use of the anesthetic MS-222 (tricaine methanesulfonate), rather than lowering body temperature with a cold water bath to prepare reptiles and amphibians for physiological experiments or euthanasia. Indeed, the most recent edition of the American Veterinary Medical Association (AVMA) Guidelines for the Euthanasia of Animals proclaims that chilling in water is not an appropriate method and advocates for the usage of MS-222 or other anesthetics. However, prominent researchers have responded to this position by highlighting evidence that cooling ectothermic vertebrates is, in fact, an effective and appropriate method. Furthermore, MS-222 is a known voltage-gated Na+ channel blocker, and this anesthetic’s impact on the physiology of excitable tissues suggests that its use might be incompatible with experiments on nerve and muscle tissues. In the present study, I examined the effects of MS-222 at a concentration of 1.5 g/l on nerve, skeletal muscle, and cardiac muscle physiology of frogs. I found that immersion of frogs in this anesthetic blocked basic nerve and muscle physiology, making the frogs unsuitable for laboratory experiments. Applying MS-222 directly to the sciatic nerve dramatically blocked normal excitation-contraction coupling in skeletal muscle preparations, and direct application to the heart caused the organs to stop contracting. Based on these results, I conclude that MS-222 at the concentration studied may be incompatible with physiological preparations that rely on electrically excitable tissues for their normal function. Physiology educators who must use MS-222 with frogs should empirically determine an appropriate dosage and recovery time before using the anesthetic in the teaching laboratory.
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Tennant, M., S. R. Bruce, and L. D. Beazley. "Survival of ganglion cells which form the retino-retinal projection during optic nerve regeneration in the frog." Visual Neuroscience 10, no. 4 (July 1993): 681–86. http://dx.doi.org/10.1017/s095252380000537x.
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AbstractDuring optic nerve regeneration in the frog, axons transiently grow along the opposite optic nerve forming a retino-retinal projection. In the present study, we crushed the left optic nerve in the frog Litoria (Hyla) moorei and later applied horseradish peroxidase (HRP) or diamidino yellow (DY) to the right optic nerve. In one series, retinae were examined 3 days after application of the tracer. The retino-retinal projection was found to be maximal at 5 weeks, fell significantly by 7 weeks, and returned to close-to-normal levels by 24 weeks. In a second series, we applied DY at 5 weeks as before but did not sacrifice the frogs until 7 weeks. Numbers of labeled ganglion cells were not significantly different from those frogs in the first series labeled and examined at 5 weeks. We conclude that ganglion cells giving rise to the retino-retinal projection had not died in appreciable numbers, presumably being sustained by collateral axons in the brain.
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FLANIGAN, JAMES E., PHILIP C. WITHERS, and MICHAEL GUPPY. "In Vitro Metabolic Depression of Tissues from the Aestivating Frog Neobatrachus Pelobatoides." Journal of Experimental Biology 161, no. 1 (November 1, 1991): 273–83. http://dx.doi.org/10.1242/jeb.161.1.273.
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The desert frog Neobatrachus pelobatoides reduced its resting metabolism in vivo by 60–70% during 5–7 weeks of aestivation (summer dormancy). The rate ofoxygen consumption (V·OO2) of isolated and intact skeletal muscle, measured in vitro, was 70% lower for aestivating frogs compared with non-aestivating frogs. The cause of the reduced V·OO2 of aestivating frog muscle must lie in the tissue itself rather than being induced by external factors such as oxygen supply or bloodborne metabolites (because these were identical in the in vitro assay conditions), by any short-term effects produced by hormones (as these would have been washed out of the tissues during incubation) or by tissue dehydration (as the tissues from aestivating frogs had rehydrated to non-aestivating levels). The reduced in vitro muscle V·OO2 accounted for 60–77% of the frogs in vivo metabolic depression that accompanied aestivation. Other tissues of the aestivating frog, namely intestine, liver, skin and fat, did not have a reduced in vitro V·OO2. We suggest that metabolic depression is initiated by reduced energy demand in cells and this consequently leads to reduced energy production.
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John-Alder, Henry B., Peter J. Morin, and Sharon Lawler. "Thermal Physiology, Phenology, and Distribution of Tree Frogs." American Naturalist 132, no. 4 (October 1988): 506–20. http://dx.doi.org/10.1086/284868.
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Kargo, William J., and Simon F. Giszter. "Afferent Roles in Hindlimb Wipe-Reflex Trajectories: Free-Limb Kinematics and Motor Patterns." Journal of Neurophysiology 83, no. 3 (March 1, 2000): 1480–501. http://dx.doi.org/10.1152/jn.2000.83.3.1480.
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The hindlimb wiping reflex of the frog is an example of a targeted trajectory that is organized at the spinal level. In this paper, we examine this reflex in 45 spinal frogs to test the importance of proprioceptive afferents in trajectory formation at the spinal level. We tested hindlimb to hindlimb wiping, in which the wiping or effector limb and the target limb move together. Loss of afferent feedback from the wiping limb was produced by cutting dorsal roots 7–9. This caused altered initial trajectory direction, increased ankle path curvature, knee-joint velocity reversals, and overshooting misses of the target limb. We established that these kinematic and motor-pattern changes were due mainly to the loss of ipsilateral muscular and joint afferents. Loss of cutaneous afferents alone did not alter the initial trajectory up to target limb contact. However, there were cutaneous effects in later motor-pattern phases after the wiping and target limb had made contact: The knee extension or whisk phase of wiping was often lost. Finally, there was a minor and nonspecific excitatory effect of phasic contralateral feedback in the motor-pattern changes after deafferentation. Specific muscle groups were altered as a result of proprioceptive loss. These muscles also showed configuration-based regulation during wiping. Biceps, semitendinosus, and sartorius (all contributing knee flexor torques) all were regulated in amplitude based on the initial position of the limb. These muscles contributed to an initial electromyographic (EMG) burst in the motor pattern. Rectus internus and semimembranosus (contributing hip extensor torques) were regulated in onset but not in the time of peak EMG or in termination of EMG based on initial position. These two muscles contributed to a second EMG burst in the motor pattern. After deafferentation the initial burst was reduced and more synchronous with the second burst, and the second burst often was broadened in duration. Ankle path curvature and its degree of change after loss of proprioception depended on the degree of joint staggering used by the frog (i.e., the relative phasing between knee and hip motion) and on the degree of motor-pattern change. We examined these variations in 31 frogs. Twenty percent (6/31) of frogs showed largely synchronous joint coordination and little effect of deafferentation on joint coordination, end-point path, or the underlying synchronous motor pattern. Eighty percent of frogs (25/31) showed some degree of staggered joint coordination and also strong effects of loss of afferents. Loss of afferents caused two major joint level changes in these frogs: collapse of joint phasing into synchronous joint motion and increased hip velocity. Fifty percent of frogs (16/31) showed joint-coordination changes of type (1) without type (2). This change was associated with reduction, loss, or collapse of phasing of the sartorius, semitendinosus and biceps (iliofibularis) in the initial EMG burst in the motor pattern. The remaining 30% (9/31) of frogs showed both joint-coordination changes 1 and 2. These changes were associated with both the knee flexor EMG changes seen in the other frogs and with additional increased activity of rectus internus and semimembranosus muscles. Our data show that multiple ipsilateral modalities all play some role in regulating muscle activity patterns in the wiping limb. Our data support a strong role of ipsilateral proprioception in the process of trajectory formation and specifically in the control of limb segment interactions during wiping by way of the regulation and coordination of muscle groups based on initial limb configuration.
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Kirschner, L. B. "Basis for apparent saturation kinetics of Na+ influx in freshwater hyperregulators." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 254, no. 6 (June 1, 1988): R984—R988. http://dx.doi.org/10.1152/ajpregu.1988.254.6.r984.
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Uptake of Na+ by intact frogs has been reported to show saturation kinetics at low external concentrations (less than 2 mM); yet other evidence shows that the transport system is far from saturated in this concentration range. The saturation behavior was reproduced here in isolated frog skins that were then used as appropriate models for investigating the paradox. When the skin was bathed by 2 mM Na+ outside and open circuited, influx (JNain) was near maximum. If, under these conditions, the skin was short circuited, JNain increased threefold. Alternatively, if Cl- permeability was increased in the open-circuited skin, JNain doubled. Both perturbations uncouple JNain from the efflux of a cation (nominally H+), which normally maintains electrical neutrality under open-circuit conditions. This suggests that the apparent saturation of JNain is caused by limiting efflux of the counterion. In confirmation of this prediction, stimulation of proton efflux markedly increased JNain. Thus the apparent Michaelis-Menten kinetics observed in frogs, and probably in other freshwater animals as well, do not represent saturation of an element in Na+ transport, either the amiloride-sensitive apical channel or the basolateral Na+-K+-ATPase.
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Mason, Matthew J., and Peter M. Narins. "Vibrometric studies of the middle ear of the bullfrog Rana catesbeiana I. The extrastapes." Journal of Experimental Biology 205, no. 20 (October 15, 2002): 3153–65. http://dx.doi.org/10.1242/jeb.205.20.3153.
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SUMMARY Laser vibrometry was used to measure the vibration velocity at different points on the ossicular apparatus of the bullfrog Rana catesbeiana in response to free-field sound. The ascending process of the extrastapes,neglected in most accounts of frog middle ear mechanics, supports a rocking motion of the extrastapes and is critical to the normal function of the ossicular apparatus. The articulation between extrastapes and the bony stapes shaft acts as a hinge, although movement at this hinge is usually small. The ratio of tympanic membrane to footplate vibration velocity is significantly greater in male frogs than in female frogs. Differences in this ratio between male and female frogs are probably mainly due to flexion between the extrastapes and stapes rather than to differences in the coupling between tympanic membrane and extrastapes. It is argued that flexibility in the ossicular system represents a protective mechanism in frogs, and functional analogies are drawn between the stapes/extrastapes system of frogs and the tri-ossicular system of mammals.
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Saltiel, Philippe, Kuno Wyler-Duda, Andrea D'Avella, Matthew C. Tresch, and Emilio Bizzi. "Muscle Synergies Encoded Within the Spinal Cord: Evidence From Focal Intraspinal NMDA Iontophoresis in the Frog." Journal of Neurophysiology 85, no. 2 (February 1, 2001): 605–19. http://dx.doi.org/10.1152/jn.2001.85.2.605.
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This paper relates to the problem of the existence of muscle synergies, that is whether the CNS command to muscles is simplified by controlling their activity in subgroups or synergies, rather than individually. We approach this problem with two methods that have been recently introduced: intraspinal N-methyl-d-aspartate (NMDA) microstimulation and a synergy-extracting algorithm. To search for a common set of synergies encoded for by the spinal cord whose combinations would account for a large range of electromyographic (EMG) patterns, we chose, rather than examining a large range of natural behaviors, to chemically microstimulate a large number of spinal cord interneuronal sites in different frogs. A possible advantage of this complementary method is that it is task-independent. Visual inspection suggested that the NMDA-elicited EMG patterns recorded from 12 leg muscles might indeed be constructed from smaller subgroups of muscles whose activity co-varied, suggestive of synergies. We used a modification of our extracting computational algorithm whereby a nonnegative least-squares method was employed to iteratively update both the synergies and their coefficients of activation in reconstructing the EMG patterns. Using this algorithm, a limited set of seven synergies was found whose linear combinations accounted for more than 91% of the variance in the pooled EMG data from 10 frogs, and more than 96% in individual frogs. The extracted synergies were similar among frogs. Further, preferred combinations of these synergies were clearly identified. This was found by extracting smaller sets of four, five, or six synergies and fitting each synergy from those sets as a combination from the set of seven synergies extracted from the same frog; the synergy combinations from each frog were then pooled together to examine their frequency of occurrence. Concordance with this method of identifying synergy combinations was found by examining how the synergies from the set of seven correlated pair-wise as they reconstructed the EMG data. These results support the existence of muscle synergies encoded within the spinal cord, which through preferred combinations, account for a large repertoire of spinal cord motor output. These findings are contrasted with previous approaches to the problem of synergies.
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Borkent, Art, and Peter Belton. "Attraction of female Uranotaenia lowii (Diptera: Culicidae) to frog calls in Costa Rica." Canadian Entomologist 138, no. 1 (February 2006): 91–94. http://dx.doi.org/10.4039/n04-113.
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AbstractDuring a survey of frog-biting corethrellid midges in Costa Rica, we collected 79 female Uranotaenia lowii Theobald, mosquitoes known to bite frogs, from seven lowland localities using the recorded calls of a frog. The calls of male barking tree frogs, Hyla gratiosa LeConte, were repeated about once per second, lasted about 0.15 s, and had a fundamental frequency near 450 Hz. We suggest that this frequency is within the range of acoustic sensitivity of the female mosquito antennae. Males of several families of Nematocera use sound to detect flying females of their own species, but we believe ours is the first observation of female mosquitoes being attracted by the sound of a host.
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Miyachi, Yukihisa, Takahisa Koike, Kenzo Muroi, Tomoko Kanao, Taro Kawamoto, and Takeshi Yamada. "Marked depression of radiation-induced emesis in frogs following prior exposure to a brief dose of X-rays." Canadian Journal of Physiology and Pharmacology 80, no. 8 (August 1, 2002): 828–32. http://dx.doi.org/10.1139/y02-108.
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Acute emesis response to harmful doses of X-rays on frogs (Rana porosa porosa) was examined. Results showed that the number of radioemesis events following exposure to 0.85 Gy was slightly higher than in the sham control animals. The increase in emesis action became more pronounced when the total dose of radiation was raised to 2.5 Gy. Only 1 frog out of a total of 12 did not show vomiting following radiation, while no response was observed in sham control animals. Note that animals in which the low dose rate of radiation was applied to whole body did not display any changes in the emesis response relative to control animals. The present studies, and those by others, showed that a brief dose of X-rays prior to a second exposure to a sub-lethal dose might induce a tolerance to radiation. An additional experiment was conducted to examine whether a small conditioning dose could induce a depression of radioemesis (tolerance) following an exposure to high dose X-ray. With prior exposure to 0.3 Gy, only 1 frog out of a total of 5 frogs vomited as a result of radiation exposure. Suppression of the emetic response became significant when the pre-radiation dose was decreased to 0.1 Gy. On the contrary, increasing the small conditioning dose to 0.5 Gy resulted in a remarkable rise of radiation-induced emesis. This results indicate that exposure to the smaller dose of X-rays elicits a tolerance effect to toxic dose level of radiation.Key words: emesis, hormesis, low-dose X-rays, resistance, frog.
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Wu, Nicholas C., Callum McKercher, Rebecca L. Cramp, and Craig E. Franklin. "Mechanistic basis for loss of water balance in green tree frogs infected with a fungal pathogen." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 317, no. 2 (August 1, 2019): R301—R311. http://dx.doi.org/10.1152/ajpregu.00355.2018.
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Chytridiomycosis, a lethal skin disease caused by the fungal pathogen Batrachochytrium dendrobatidis ( Bd), disrupts skin function of amphibians, interfering with ionic and osmotic regulation. To regulate fungal loads, amphibians increase their rate of skin sloughing. However, sloughing also causes a temporary loss of ionic and osmotic homeostasis due to disruption of the skin, a key osmoregulatory organ. The combined effects of increased sloughing frequency and chytridiomycosis contribute to the high rates of mortality from Bd infections. However, the mechanisms responsible for the loss of cutaneous osmotic regulation remain unknown. We measured the changes in whole animal water uptake rates, in vitro transcutaneous water fluxes across the ventral skin, and the mRNA expression of epithelial water transport proteins (aquaporins, AQPs) and junctional proteins in Bd-infected and uninfected Litoria caerulea skin. We hypothesize that infected frogs would show reduction/inhibition in cutaneous water transporters responsible for regulating water balance, and sloughing would exacerbate cutaneous water fluxes. We found that infected, nonsloughing frogs had an impaired rate of water uptake and showed increased rates of in vitro water efflux across the ventral skin. In uninfected frogs, the expression of AQPs and junction genes increased significantly with sloughing, which may assist in regulating cutaneous water movements and barrier function in the newly exposed skin. In contrast, infected frogs did not show this postsloughing increase in AQP gene expression. The combination of increased sloughing frequency, impaired water uptake rates, and increased rates of water loss likely contributes to the loss of osmotic homeostasis in frogs infected with Bd.
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Zimmerman, Sarah L., James Frisbie, David L. Goldstein, Jennifer West, Kevin Rivera, and Carissa M. Krane. "Excretion and conservation of glycerol, and expression of aquaporins and glyceroporins, during cold acclimation in Cope's gray tree frog Hyla chrysoscelis." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 292, no. 1 (January 2007): R544—R555. http://dx.doi.org/10.1152/ajpregu.00434.2006.
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Cope's gray tree frog Hyla chrysoscelis accumulates glycerol during cold acclimation. We hypothesized that, during this process, gray tree frogs adjust renal filtration and/or reabsorption rates to retain accumulated glycerol. During cold acclimation, plasma concentrations of glycerol rose >200-fold, to 51 mmol/l. Although fractional water reabsorption decreased, glomerular filtration rate (GFR) and, consequently, urine flow were <5% of warm levels, and fractional glycerol reabsorption increased. In contrast, dehydrated frogs increased fractional water reabsorption, decreased GFR, and did not accumulate glycerol. We hypothesized that expression of proteins from the aquaporin (AQP)/glyceroporin (GLP) family was associated with changing patterns of water and glycerol movement. We cloned the cDNA for three such proteins, quantified mRNA expression in nine tissues using real-time quantitative PCR, and functionally characterized them using a Xenopus oocyte expression system. HC-1, an AQP1-like water channel conferring low glycerol permeability, is expressed ubiquitously in warm- and cold-acclimated tissues. HC-2, a water channel most similar to AQP2, is primarily expressed in organs of osmoregulation. HC-3, which is most similar to AQP3, is functionally characterized as a GLP, with low permeability to water but high permeability to glycerol. Aspects of expression levels and functional characteristics varied between cold and warm conditions for each of the three AQPs, suggesting a complex pattern of involvement in osmoregulation related to thermal acclimation.
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Storey, K. B., and T. P. Mommsen. "Effects of temperature and freezing on hepatocytes isolated from a freeze-tolerant frog." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 266, no. 5 (May 1, 1994): R1477—R1482. http://dx.doi.org/10.1152/ajpregu.1994.266.5.r1477.
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Metabolically active hepatocytes prepared from freeze-tolerant wood frogs, Rana sylvatica, were used to examine the direct effects of temperature and freezing on cryoprotectant synthesis and to assess the effectiveness of the natural cryoprotectant glucose in the freezing preservation of the isolated cells. Freshly isolated hepatocytes showed slow leakage of lactate dehydrogenase, readily synthesized urea, and oxidized a variety of 14C-labeled substrates. Effects of temperature on glucose production by isolated hepatocytes showed a normal Arrhenius relationship. However, compared with 0 degrees C control cells, either incubation at higher temperatures or freezing at -3 degrees C reduced the activity of glycogen phosphorylase alpha. These data suggest that the freezing-induced cryoprotectant production that occurs in vivo is not due to direct action of either low temperature or freezing on liver cell metabolism. The natural cryoprotectant glucose was also an excellent cryoprotectant of hepatocytes in vitro. In the absence of glucose, freezing caused a substantial leakage of lactate dehydrogenase from isolated hepatocytes, the rate of leakage increasing as freezing temperature decreased. Addition of 200-600 mM glucose to the incubation medium (similar to natural levels) fully protected cells against damage during freezing at -4 or -8 degrees C, normal freezing temperatures experienced by these frogs. Glucose also greatly improved freezing survival of isolated frog hepatocytes at ultralow temperatures (-80 or -196 degrees C).
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Tattersall, Glenn J., Suzanne Currie, and Danielle M. LeBlanc. "Pulmonary and cutaneous O2 gas exchange: a student laboratory exercise in the frog." Advances in Physiology Education 37, no. 1 (March 2013): 97–105. http://dx.doi.org/10.1152/advan.00087.2012.
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Gas exchange in animals is ultimately diffusion based, generally occurring across dedicated respiratory organs. In many aquatic amphibians, however, multiple modes of gas exchange exist, allowing for the partitioning of O2 uptake and CO2 excretion between respiratory organs with different efficiencies. For example, due to the physical properties of O2 being vastly different between air and water phases, the lung and skin play disproportionately important roles in O2 uptake. Many aquatic frogs are renowned for their cutaneous gas exchange capacity, where often the majority of CO2 is excreted across the skin. Furthermore, the roles of these gas exchange organs change with the animal's behavior. Under diving conditions, most of the frog's gas exchange needs must be met by the skin. In this article, we describe an interactive undergraduate laboratory that allows a class of students to share equipment while assessing pulmonary and cutaneous respiration in frogs provided with an air/water choice and under enforced dive conditions. Concepts explored in this laboratory exercise include animal energetics, diving reflex, pulmonary and cutaneous gas exchange processes, diffusion-based gas flux, and O2 debt.
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Giszter, S. F., J. McIntyre, and E. Bizzi. "Kinematic strategies and sensorimotor transformations in the wiping movements of frogs." Journal of Neurophysiology 62, no. 3 (September 1, 1989): 750–67. http://dx.doi.org/10.1152/jn.1989.62.3.750.
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1. Spinal frogs are known to make coordinated and successful wiping movements to almost all places on the body and legs. Such wiping movements involve a sensorimotor transformation. Information from both the spatial locations of stimuli on the skin and the body configuration of the frog is transformed into a set of motor commands that generate body movements adequate to successfully remove the irritant. The spinal cord itself therefore has a limited capacity for sensorimotor transformations. 2. We examined the kinematics of wiping motions in both spinal and intact leopard frogs and bullfrogs. This data was used to assess the flexibility, precision, and strategy of the kinematic sensorimotor transformations used during wiping. The movements involved the use of redundant degrees of freedom in the limbs. Thus many possible movements or solutions could generate successful wiping. This redundancy allows motor-equivalent movements to be used by the frog. 3. Movements were examined in two dimensions by the use of VHS shuttered-video recording and in three dimensions with the use of a WATSMART system of infrared diodes and cameras. The kinematic analysis was applied to those motions in which the limbs did not interact with kinematic constraints, such as the surface of the substrate or body. These unconstrained motions are directly related to motor commands and thus more easily interpreted. 4. Wiping movements to the back were retained in essentially the same form in both spinal and intact frogs. In both cases wiping had four phases with a fifth occasionally present. The phases included flexion, placing, aiming, and whisking, with occasional extension and multiply repeated wipes. However, the aiming phase was often very brief or absent in this data, and flexion was sometimes omitted in multiple wipes. We found that the placing posture was adjusted in a simple way in response to variations in the location of the target stimulus. The rostrocaudal position of the foot tip was strongly and linearly related to the rostrocaudal stimulus location. 5. During the placing posture, joint angles as well as the limb tip in back wipes had linear relationships to the stimulus' rostrocaudal coordinate. The limb configuration used by the frog allowed a strategy of linear (and potentially independent) postural adjustment of joint angle to stimulus position to generate almost linear endpoint adjustments in the placing phase of wiping. This solution to the ill-posed problem of choosing a joint angle for the placing posture in back-wiping may be computationally simple.(ABSTRACT TRUNCATED AT 400 WORDS)
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Purnamasari, Sry, and Muhammad Wahyu Setiyadi. "PENGARUH ZAT KIMIA PADA BERBAGAI SUHU TERHADAP DENYUT JANTUNG KATAK (Rana sp.) DALAM UPAYA PENGEMBANGAN BUKU PETUNJUK PRAKTIKUM FISIOLOGI HEWAN." Bioscientist : Jurnal Ilmiah Biologi 7, no. 2 (December 30, 2019): 123. http://dx.doi.org/10.33394/bjib.v7i2.2388.
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The purpose of this study is to determine the effect of chemicals on various temperatures in the heart of frogs (Rana sp.) And to compile valid animal physiology practical instructions. This research is a type of experimental research (true experimental) and this research approach is a qualitative approach. Samples were given 3 different treatments, namely controls with room temperature of 250C-300C, temperature of 00C-100C, and 300C-400C. The results of the study using ANOVA (Analysis of Variance) showed the effect of NaCl solution on the frog heart rate (Rana sp.) Namely Fcount of 5.18 while Ftable of 3.59 so that the results of this study were declared significant. While the effect of saline solution on the frog heart rate (Rana sp.) Is Fcount of 1.78 while Ftable is 3.59 so the results of this study are declared non-significant. So it can be concluded that, NaCl solution at various temperatures significantly influences the frog heart rate (Rana sp.), While saline solution at various temperatures does not significantly influence the frog heart rate (Rana sp.). The process of developing this animal physiology practical guide uses a 3-D development model, which consists of the define, design, and develope stages. The results of the study showed that the practicum instructions for animal physiology were valid, said to be valid because the practicum instructions prepared and developed had met the "valid" criteria.
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Huang, Min Yi, Ren Yan Duan, and Xiao Li Ji. "Amphibian as a Model to Study Environmental Problem." Applied Mechanics and Materials 71-78 (July 2011): 3179–82. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.3179.
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In order to obtain a better insight of the possible threat of environmental factor to wildlife, especially to amphibians, we studied influences of dicofol on heart rate inR. nigromaculataby applying biological signal recording and monitoring system.R. nigromaculatawas injected in ventral lymph follicle in different doses of dicofol solution, and then observed the changes of heart rate after 7 days. The results showed that with the concentration of dicofol solution increasing, the heart rate, systolic tension and diastolic tension changed. The aim of this research is to discuss the cause of dicofol on the physiology in frogs. It can be concluded that dicofol affects the electronic activity of the frog’s heart.
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St-Pierre, Julie, Glenn J. Tattersall, and Robert G. Boutilier. "Metabolic depression and enhanced O2 affinity of mitochondria in hypoxic hypometabolism." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 279, no. 4 (October 1, 2000): R1205—R1214. http://dx.doi.org/10.1152/ajpregu.2000.279.4.r1205.
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This study examined whether the steady-state hypometabolism seen in overwintering frogs ( Rana temporaria) is reflected at the mitochondrial level either by a reduction in their resting (state 4) and active (state 3) respiration rates and/or by increases in O2 affinity. We isolated mitochondria from the skeletal muscle of cold-submerged frogs at different stages during their hibernation in normoxic and hypoxic water. A modest metabolic depression at the whole animal level (normoxic submergence) was not associated with a reduction in mitochondrial state 4 and state 3 respiration rates. However, mitochondria isolated from frogs that were submerged for 1 mo manifested an increase in their O2 affinity compared with controls and with animals submerged for 4 mo. Hypometabolism was more pronounced at the whole animal level during hypoxic submergence and was accompanied by 1) a reduction in mitochondrial state 4 and state 3 rates and 2) an increase in the O2affinity of mitochondria. These findings demonstrate that metabolic depression can be reflected at all levels of biological organization in hypoxia-tolerant animals.
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Shibata, Yuki, Takahiro Sano, Nobuhito Tsuchiya, Reiko Okada, Hiroshi Mochida, Shigeyasu Tanaka, and Masakazu Suzuki. "Gene expression and localization of two types of AQP5 inXenopus tropicalisunder hydration and dehydration." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 307, no. 1 (July 1, 2014): R44—R56. http://dx.doi.org/10.1152/ajpregu.00186.2013.
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Two types of aquaporin 5 (AQP5) genes ( aqp-xt5a and aqp-xt5b) were identified in the genome of Xenopus tropicalis by synteny comparison and molecular phylogenetic analysis. When the frogs were in water, AQP-xt5a mRNA was expressed in the skin and urinary bladder. The expression of AQP-xt5a mRNA was significantly increased in dehydrated frogs. AQP-xt5b mRNA was also detected in the skin and increased in response to dehydration. Additionally, AQP-xt5b mRNA began to be slightly expressed in the lung and stomach after dehydration. For the pelvic skin of hydrated frogs, immunofluorescence staining localized AQP-xt5a and AQP-xt5b to the cytoplasm of secretory cells of the granular glands and the apical plasma membrane of secretory cells of the small granular glands, respectively. After dehydration, the locations of both AQPs in their respective glands did not change, but AQP-xt5a was visualized in the cytoplasm of secretory cells of the small granular glands. For the urinary bladder, AQP-xt5a was observed in the apical plasma membrane and cytoplasm of a number of granular cells under normal hydration. After dehydration, AQP-xt5a was found in the apical membrane and cytoplasm of most granular cells. Injection of vasotocin into hydrated frogs did not induce these changes in the localization of AQP-xt5a in the small granular glands and urinary bladder, however. The results suggest that AQP-xt5a might be involved in water reabsorption from the urinary bladder during dehydration, whereas AQP-xt5b might play a role in water secretion from the small granular gland.
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Jackson, Donald C., and Gordon R. Ultsch. "Physiology of hibernation under the ice by turtles and frogs." Journal of Experimental Zoology Part A: Ecological Genetics and Physiology 313A, no. 6 (March 26, 2010): 311–27. http://dx.doi.org/10.1002/jez.603.
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Tattersall, G. J., and R. G. Boutilier. "Does behavioural hypothermia promote post-exercise recovery in cold-submerged frogs?" Journal of Experimental Biology 202, no. 5 (March 1, 1999): 609–22. http://dx.doi.org/10.1242/jeb.202.5.609.
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At the low temperatures of the overwintering environment of the frog Rana temporaria, small changes in ambient temperature have large effects on metabolism and behaviour, especially since Q10 values are often greatly elevated in the cold. How the overwintering aquatic frog copes with variable thermal environments in terms of its overall activity metabolism and recovery from pursuit by predators is poorly understood, as is the role of behavioural thermoregulation in furthering recovery from intense activity. Exhaustive exercise was chosen as the method of evaluating activity capacity (defined by time to exhaustion, total distance swum and number of leg contractions before exhaustion) and was determined at 1.5 and 7 degreesC. Other cohorts of frogs were examined at both temperatures to determine the metabolic (acid-base, lactate, glucose, ATP and creatine phosphate) and respiratory responses to exercise in cold-submerged frogs. Finally, temperature preference before and after exercise was determined in a thermal gradient to define the importance of behavioural thermoregulation on the recovery rates of relevant metabolic and respiratory processes. Activity capacity was significantly reduced in frogs exercised at 1.5 versus 7 degreesC, although similar levels of tissue acid-base metabolites and lactate were reached. Blood pH, plasma PCO2 and lactate levels recovered more rapidly at 1.5 degreesC than at 7 degreesC; however, intracellular pH and the recovery of tissue metabolite levels were independent of temperature. Resting aerobic metabolic rates were strongly affected by temperature (Q10=3.82); however, rates determined immediately after exercise showed a reduced temperature sensitivity (Q10=1.67) and, therefore, a reduced factorial aerobic scope. Excess oxygen consumption recovered to resting values after 5–6.25 h, and 67 % recovery times tended to be slightly faster at the lower temperatures. Exercise in the cold, therefore, provided an immediately higher factorial scope, which could be involved in the faster rate of recovery of blood lactate levels in the colder frogs. In addition, exercise significantly lowered the preferred temperature of the frogs from 6.7 to 3.6 degreesC for nearly 7 h, after which they returned to their normal, unstressed preferred temperatures. Thus, a transient behavioural hypothermia in the skin-breathing, overwintering frog may be an important strategy for minimising post-exercise stress and maintaining aerobic metabolism during recovery from intense activity.
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Rossi, Maria Lisa, Gemma Rubbini, Luciana Gioglio, Marta Martini, and Riccardo Fesce. "Exposure to reduced gravity impairs junctional transmission at the semicircular canal in the frog labyrinth." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 298, no. 2 (February 2010): R439—R452. http://dx.doi.org/10.1152/ajpregu.00673.2009.
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The effects of microgravity on frog semicircular canals have been studied by electrophysiological and morphological approaches. Reduced gravity (microG) was simulated by a random positioning machine (RPM), which continually and randomly modified the orientation in space of the anesthetized animal. As this procedure stimulates the semicircular canals, the effect of altered gravity was isolated by comparing microG-treatment with an identical rotary stimulation in the presence of normal gravity (normoG). Electrophysiological experiments were performed in the isolated labyrinth, extracted from the animals after the treatment, and mounted on a turntable. Junctional activity was measured by recording quantal events (mEPSPs) and spikes from the afferent fibers close to the junction, at rest and during rotational stimulation. MicroG-treated animals displayed a marked decrease in the frequency of resting and evoked mEPSP discharge, vs. both control and normoG (mean decrease ∼50%). Spike discharge was also depressed: 57% of microG-treated frogs displayed no spikes at rest and during rotation at 0.1 Hz, vs. 23–31% of control or normoG frogs. Among the firing units, during one cycle of sinusoidal rotation at 0.1 Hz microG-treated units emitted an average of 41.8 ± 8.06 spikes, vs. 77.2 ± 8.19 in controls. Patch-clamp analysis on dissociated hair cells revealed altered Ca2+ handling, after microG, consistent with and supportive of the specificity of microG effects. Marked morphological signs of cellular suffering were observed after microG, mainly in the central part of the sensory epithelium. Functional changes due to microgravity were reversible within a few days.
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Kouba, A., E. Willis, C. Vance, S. Hasenstab, S. Reichling, J. Krebs, L. Linhoff, M. Snoza, C. Langhorne, and J. Germano. "116 DEVELOPMENT OF ASSISTED REPRODUCTION TECHNOLOGIES FOR THE ENDANGERED MISSISSIPPI GOPHER FROG (RANA SEVOSA) AND SPERM TRANSFER FOR IN VITRO FERTILIZATION." Reproduction, Fertility and Development 24, no. 1 (2012): 170. http://dx.doi.org/10.1071/rdv24n1ab116.
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Species-specific differences in breeding strategies and physiology have limited the application of assisted reproductive technologies (ART) for critically endangered amphibians in captive assurance colonies. In 2006, the Memphis Zoo (MZ) initiated a program to develop ART for the critically endangered Mississippi gopher frog after natural breeding failed. Standard gamete collection and IVF developed by MZ for reproducing endangered toads such as the Wyoming or boreal toad were applied to the gopher frog with little success, especially hormonal therapy for sperm production. Using the leopard frog as a model species for Ranids, we tested the time and dose dependence of a luteinizing hormone releasing hormone analogue (LHRHa) and hCG on sperm quantity and quality. Initial findings from the leopard frog study were critical in designing the study on gopher frogs. Our objectives were to (1) compare 2 different hormones administered intraperitoneal (500 IU hCG vs 15 μg LHRHa) or their combination on spermiation in gopher frogs; (2) develop in vivo oocyte maturation and ovulation protocols using LHRHa (15 μg) and hCG (500 IU); and (3) transfer this technology to another institution as proof of principle. In gopher frogs, 100 and 83% of the males produced sperm in response to the LHRHa and the combination treatment, respectively, whereas only 16% responded to hCG alone. Sperm concentration peaked at 1 h post-administration for all treatments, with the LHRH/hCG cocktail treatment producing the highest concentration of sperm (mean = 4.6 × 106 ± 1.2 × 106 sperm mL–1, n = 6). No differences in motility were observed between treatments (P > 0.05). For females, a series of priming hormones of hCG and LHRHa were given several months before an ovulatory hormone regimen resulting in ovulation by 100% of the females (n = 6), whereas animals not primed failed to ovulate (n = 4). These 3 separate priming and IVF trials conducted between 2008 and 2010 resulted in each female laying ∼2000 eggs, with an average fertilization rate of 76% for inseminated eggs and hundreds of tadpoles produced. These IVF tadpoles represent the first captive reproduction of gopher frogs and highlight how ART can be applied to conservation and genetic management of threatened species. Subsequently, we tested our IVF protocols on gopher frogs at Omaha's Henry Doorly Zoo using fresh (collected on site) and chilled, shipped sperm from MZ. We collected 6169 eggs from 9 hormone-primed females with all animals ovulating. A portion of the total eggs ovulated were inseminated, resulting in 2401 fertilized eggs (38.9% of total eggs collected) across 18 different male–female pairings leading to viable tadpoles. In addition, sperm transferred overnight from the MZ produced 202/441 fertilized eggs (46%). The transfer of this technology and production of endangered amphibians using chilled, shipped sperm from live animals is a conservation milestone that can be applied to other captive breeding programs.
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Chapman, Angela M., and Elizabeth A. Debski. "Neuropeptide Y immunoreactivity of a projection from the lateral thalamic nucleus to the optic tectum of the leopard frog." Visual Neuroscience 12, no. 1 (January 1995): 1–9. http://dx.doi.org/10.1017/s0952523800007264.
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AbstractUsing rhodamine-labelled latex beads as a retrograde tracer, we have shown that a subset of the neurons projecting from the lateral thalamic nucleus to the optic tectum of the leopard frog are neuropeptide Y-like immunoreactive (NPY-IR). In juvenile frogs, approximately twice as many lateral thalamic nucleus cells from this area project to the ipsilateral tectum as project to the contralateral tectum. NPY-IR cells make up 25% of the projection to the ipsilateral tectum and 13% of the projection to the contralateral tectum. The ipsilateral NPY-IR projection from the lateral nucleus was present in tadpoles and was similar in its characteristics to that found in the juvenile frog. However, the contralateral tectal projection was virtually nonexistent in these animals. The results of these experiments suggest that NPY from the lateral nucleus is released into the ipsilateral tectal neuropil in both the developing and adult frog.
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Liparoto, Anita, Daniele Canestrelli, Roberta Bisconti, Claudio Carere, and David Costantini. "Biogeographic history moulds population differentiation in ageing of oxidative status in an amphibian." Journal of Experimental Biology 223, no. 21 (September 24, 2020): jeb235002. http://dx.doi.org/10.1242/jeb.235002.
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ABSTRACTRegulation of oxidative status plays a substantial role in physiological ageing. However, we know little about age-related changes of oxidative status in wild animals, and even less about the role of population history in moulding ageing rates. We addressed these questions by means of a common garden experiment, using the Tyrrhenian tree frog Hyla sarda as the study species. This species underwent a range expansion from northern Sardinia (source) up to Corsica (newly founded) during the Late Pleistocene, and then the two populations became geographically isolated. We found that, at the beginning of the experiment, Sardinian and Corsican frogs had similar concentrations of all oxidative status markers analysed. One year later, Corsican frogs had higher oxidative stress and suffered higher mortality than Sardinian frogs. Our results suggest the intriguing scenario that population differentiation in rates of physiological ageing owing to oxidative stress might be an overlooked legacy of past biogeographic processes.
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Donohoe, Paul H., Timothy G. West, and Robert G. Boutilier. "Respiratory, metabolic, and acid-base correlates of aerobic metabolic rate reduction in overwintering frogs." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 274, no. 3 (March 1, 1998): R704—R710. http://dx.doi.org/10.1152/ajpregu.1998.274.3.r704.
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Aerobic metabolic rates (M˙o 2) and respiratory quotients (RQ = CO2production/M˙o 2) were measured contemporaneously in hibernating frogs Rana temporaria (L.), submerged for 90 days at 3°C. After 3 mo of submergence in fully aerated water,M˙o 2levels were 61% of those seen at the same temperature before hibernation. Over the first 40 days of hibernation, RQ values (≤0.82) favored a lipid-based metabolism that progressively shifted to an exclusively carbohydrate metabolism (RQ = 1.01) by 90 days of hibernation. Liver glycogen concentrations fell by 68% during the first 8 wk of submergence, thereafter exhibiting a less rapid rate of utilization. Conversely, muscle glycogen concentrations remained stable over the first 2 mo of the experiment before falling by 33% over the course of the remaining 2 mo, indicating that the frog was recruiting muscle glycogen reserves to fuel metabolism. Submerged frogs exhibited an extracellular acidosis during the first week of submergence, but over the course of the next 15 wk “extracellular pH” values were not significantly different from the values obtained from the control air-breathing animals. The initial extracellular acidosis was not mirrored in the intracellular compartment, and the acid-base state was not significantly different from the control values for the first 8 wk. However, over the subsequent 8- to 16-wk period, the acid-base status shifted to a lower intracellular pH-[Formula: see text] concentration set point, indicative of a metabolic acidosis. Even so, there was no indication that the acidosis could be attributed to anaerobic metabolism, as both plasma and muscle lactate levels remained low and stable. Muscle adenylate energy charge and lactate-to-pyruvate and creatine-to-phosphocreatine ratios also remained unchanged throughout hibernation. The capacity for profound metabolic rate suppression together with the ability to match substrate use to shifts in aerobic metabolic demands and the ability to fix new acid-base homeostatic set points are highly adaptive, both in terms of survival and reproductive success, to an animal that is often forced to overwinter under the cover of ice.
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van Bergen, Y. "FASTING FROGS." Journal of Experimental Biology 208, no. 13 (July 1, 2005): iii. http://dx.doi.org/10.1242/jeb.01717.
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Reilly, Beau D., David I. Schlipalius, Rebecca L. Cramp, Paul R. Ebert, and Craig E. Franklin. "Frogs and estivation: transcriptional insights into metabolism and cell survival in a natural model of extended muscle disuse." Physiological Genomics 45, no. 10 (May 15, 2013): 377–88. http://dx.doi.org/10.1152/physiolgenomics.00163.2012.
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Green-striped burrowing frogs ( Cyclorana alboguttata ) survive in arid environments by burrowing underground and entering into a deep, prolonged metabolic depression known as estivation. Throughout estivation, C. alboguttata is immobilized within a cast-like cocoon of shed skin and ceases feeding and moving. Remarkably, these frogs exhibit very little muscle atrophy despite extended disuse and fasting. Little is known about the transcriptional regulation of estivation or associated mechanisms that may minimize degradative pathways of atrophy. To investigate transcriptional pathways associated with metabolic depression and maintenance of muscle function in estivating burrowing frogs, we assembled a skeletal muscle transcriptome using next-generation short read sequencing and compared gene expression patterns between active and 4 mo estivating C. alboguttata . This identified a complex suite of gene expression changes that occur in muscle during estivation and provides evidence that estivation in burrowing frogs involves transcriptional regulation of genes associated with cytoskeletal remodeling, avoidance of oxidative stress, energy metabolism, the cell stress response, and apoptotic signaling. In particular, the expression levels of genes encoding cell cycle and prosurvival proteins, such as serine/threonine-protein kinase Chk1, cell division protein kinase 2, survivin, and vesicular overexpressed in cancer prosurvival protein 1, were upregulated during estivation. These data suggest that estivating C. alboguttata are able to regulate the expression of genes in several major cellular pathways critical to the survival and viability of cells, thus preserving muscle function while avoiding the deleterious consequences often seen in laboratory models of muscle disuse.
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Walton, B. Michael. "Physiology and Phylogeny: The Evolution of Locomotor Energetics in Hylid Frogs." American Naturalist 141, no. 1 (January 1993): 26–50. http://dx.doi.org/10.1086/285459.
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Still, Meghan B., Amanda M. Lea, Hans A. Hofmann, and Michael J. Ryan. "Multimodal stimuli regulate reproductive behavior and physiology in male túngara frogs." Hormones and Behavior 115 (September 2019): 104546. http://dx.doi.org/10.1016/j.yhbeh.2019.06.010.
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Partridge, Lloyd D. "Frogs solve Bernstein's problem." Behavioral and Brain Sciences 9, no. 4 (December 1986): 619–20. http://dx.doi.org/10.1017/s0140525x00051505.
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Straka, H., and N. Dieringer. "Spinal plasticity after hemilabyrinthectomy and its relation to postural recovery in the frog." Journal of Neurophysiology 73, no. 4 (April 1, 1995): 1617–31. http://dx.doi.org/10.1152/jn.1995.73.4.1617.
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1. Brachial dorsal root-evoked ventral root responses were studied in the isolated brain/spinal cord preparation of frogs. One group of frogs (n = 20) had survived a hemilabyrinthectomy (HL) between 7 and 70 days. In another group of frogs (n = 30), a nerve branch to an individual labyrinthine organ was sectioned uni- or bilaterally 15 days before the recording session. In a third group of frogs (n = 5), a weight had been mounted eccentrically on the head for 15 days. A fourth group of intact frogs (n = 8) served as a control. 2. In chronic HL frogs (> or = 60 days postoperatively) the amplitudes of short- and long-latency ventral root potentials recorded on the operated side were consistently increased with respect to control values in response to all converging inputs tested. On the intact side most of these potentials were consistently increased as well, except for crossed long-latency responses after stimulation of the dorsal root on the operated side. 3. Practically identical responses were recorded in these preparations before and after the disconnection of the spinal cord from the brain stem at the level of the obex. Before this disconnection, ventral root potentials were recorded in response to electric stimulation of either one of the VIIIth nerves on the intact or on the operated side. Ventral root potentials recorded on the operated but not on the intact side were slightly increased in chronic HL frogs. 4. The time course of these changes was studied at intervals between 7 and 70 days after the lesion. The amplitudes of short-latency dorsal root-evoked ventral root potentials were increased relatively early (7-15 days) or relatively late (> or = 30 days) after HL. Ventral root potentials evoked by stimulation of either one of the N.VIII were significantly reduced in amplitude seven days after HL but normalized again or increased above control values after longer survival periods. These differences in the time courses suggest the presence of multiple, not singular mechanisms for intraspinal changes. 5. Changes in dorsal root-evoked ventral root potentials similar to those after HL were seen 15 days after a selective unilateral section of the utricular, but not after a unilateral section of the horizontal canal or saccular nerve branch. Therefore these changes were initiated either by asymmetric utricular afferent inputs or by asymmetric proprioceptive inputs resulting from lesion-induced postural deficits. 6. These two possibilities were investigated in two different sets of experiments.(ABSTRACT TRUNCATED AT 400 WORDS)
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Drummond, Gordon B., and Brian D. M. Tom. "How can we tell if frogs jump further?" Experimental Physiology 96, no. 8 (July 22, 2011): 711–15. http://dx.doi.org/10.1113/expphysiol.2011.059493.
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Drummond, Gordon B., and Brian D. M. Tom. "How can we tell if frogs jump further?" Journal of Physiology 589, no. 14 (July 15, 2011): 3409–13. http://dx.doi.org/10.1113/jphysiol.2011.211870.
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Drummond, Gordon B., and Brian D. M. Tom. "How can we tell if frogs jump further?" Clinical and Experimental Pharmacology and Physiology 38, no. 8 (July 25, 2011): 481–84. http://dx.doi.org/10.1111/j.1440-1681.2011.05541.x.
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Beazley, L. D., and J. E. Darby. "A second episode of ganglion cell death takes place when an optic nerve regenerates for a second time in the frog." Visual Neuroscience 10, no. 2 (March 1993): 297–301. http://dx.doi.org/10.1017/s0952523800003692.
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AbstractWe have previously reported that during optic nerve regeneration in the frog, 30–40% of retinal ganglion cells die, the loss being complete within 10 weeks. In the present study, we crushed the optic nerve, waited 10 weeks, and then recrushed the nerve at the same site. Retinae were examined 10 weeks later. We estimated ganglion cell numbers from cresyl-violet-stained wholemounts and found a fall of 53% compared to normals. The loss was significantly greater than the losses of 36% and 35%, respectively, in frogs which received a single optic nerve crush and were examined 10 or 20–24 weeks later. The results indicate that a second episode of ganglion cell death took place when the optic nerve regenerated a second time. We conclude that ganglion cells in the frog are not comprised of two subpopulations, only one of which intrinsically possesses the ability to regenerate.
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HANNA, GAVIN, W. JON, and W. P. JON BARNES. "Adhesion and Detachment of the Toe Pads of Tree Frogs." Journal of Experimental Biology 155, no. 1 (January 1, 1991): 103–25. http://dx.doi.org/10.1242/jeb.155.1.103.
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The mechanisms by which the toe pads of tree frogs adhere to and detach from surfaces during climbing have been studied in Osteopilus septentrionalis and other tree frogs using a variety of techniques. The experiments on attachment lend general support to the theory that toe pads stick by wet adhesion. First, the presence of a meniscus surrounding the area of contact shows that pad and surface are connected by a fluid-filled joint. Second, experiments on single toe pads of anaesthetised frogs demonstrate that the pads exhibit the velocity-dependent resistance to shear forces expected of any system employing a fluid as an adhesive mechanism. Third, the largest adhesive forces that toe pads can generate (approx. 1.2mNmm−2, calculated from data on sticking ability) are within the range that can be produced by wet adhesion. Simple measurements of the forces needed to separate a pair of metal discs joined by mucus demonstrate that both viscous forces (Stefan adhesion) and surface tension (the two components of wet adhesion) are likely to play significant roles in the tree frog's adhesive mechanism. The experiments on detachment demonstrate that toe pads are detached from surfaces by peeling, the pads being removed from the rear forwards during forward locomotion up a vertical surface. When the frogs were induced to walk backwards down this vertical slope, peeling occurred from the front of the pad rearwards. Use of a force platform to measure directly the forces exerted by the feet during climbing shows that, during forward locomotion up a vertical slope, this peeling is not accompanied by any detectable detachment forces. Such forces of detachment are seen, however, during backward walking down the slope and when belly skin comes into contact with the platform. That peeling occurs automatically during forward locomotion is supported both by observations of peeling in single toe pads of anaesthetised frogs and by the inability of frogs to adhere to vertical surfaces in a head-down orientation. Indeed, frogs on a rotating vertical surface were observed to adjust their orientations back towards the vertical whenever their deviation from the vertical reached 85.1 ±21.5°. During forward locomotion peeling seems to occur as a natural consequence of the way in which the toes are lifted off surfaces from the rear forwards, while during backward locomotion it is an active process involving the distal tendons of the toes. Note: To whom requests for offprints should be send.
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Barnes, J., J. Smith, and J. Platter. "Climbing and adhesion in tree frogs." Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 146, no. 4 (April 2007): S144—S145. http://dx.doi.org/10.1016/j.cbpa.2007.01.290.
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Knight, K. "PIPID FROGS SUCK." Journal of Experimental Biology 213, no. 12 (May 28, 2010): iii. http://dx.doi.org/10.1242/jeb.046656.
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Hamamoto, Darryl T., and Donald A. Simone. "Characterization of Cutaneous Primary Afferent Fibers Excited by Acetic Acid in a Model of Nociception in Frogs." Journal of Neurophysiology 90, no. 2 (August 2003): 566–77. http://dx.doi.org/10.1152/jn.00324.2003.
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Acetic acid applied to the hind limb of a frog evokes nocifensive behaviors, including a vigorous wiping of the exposed skin, referred to as the wiping response. The aim of this study was to examine the responses of cutaneous primary afferent fibers in frogs to acetic acid (pH 2.84–1.42) applied topically to the skin. Conventional electrophysiological methods were used to record neuronal activity from single identified primary afferent fibers with cutaneous receptive fields on the hind limb. Fibers were classified according to their conduction velocities and responses evoked by mechanical and thermal (heat and cold) stimuli. One hundred and twenty-two mechanosensitive afferent fibers were studied (44 Aβ, 60 Aδ, and 18 C fibers). Thirty-nine percent of all fibers were excited by acetic acid, but a greater percentage of Aδ (52%) and C fibers (44%) were excited than Aβ fibers (20%). Evoked responses of fibers increased with increasingly more acidic pH until the greatest responses were evoked by acetic acid at pH 2.59–2.41. Application of acetic acid at pHs <2.41 evoked less excitation, suggesting that fibers became desensitized. Similar percentages of nociceptors and low-threshold mechanoreceptors were excited by acetic acid. Thus primary afferent fibers were excited by acetic acid at pHs that have been shown to evoke the wiping response in our previous study. The results of the present study suggest that the model of acetic acid-induced nociception in frogs may be useful for studying the mechanisms by which tissue acidosis produces pain.
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Kuffler, D. P., A. Lyfenko, L. Vyklický, and V. Vlachová. "Cellular Mechanisms of Nociception in the Frog." Journal of Neurophysiology 88, no. 4 (October 1, 2002): 1843–50. http://dx.doi.org/10.1152/jn.2002.88.4.1843.
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Cellular mechanisms underlying defense reactions induced by noxious heat and acids were studied in frogs ( Rana pipiens) by measuring whole cell membrane currents in cultured dorsal root ganglion (DRG) neurons. Seventy-eight of 82 DRG neurons exposed to 3-s ramps of increasing temperature to 48°C exhibited an inward current ( I HEAT) of 490 ± 70 pA at −70 mV. I HEAT exhibited reversal at ∼10 mV with a pronounced outward rectification, suggesting opening of nonselective cation channels. In frogs, in contrast to mammals, I HEAT was not influenced by capsaicin (5 μM), capsazepine (10 μM), or ruthenium red (10 μM). In a large proportion (∼80%) of heat-sensitive DRG neurons, acids produced a large slowly inactivating sodium carried current ( I ACID) with average pH50 5.7. I ACIDwas blocked by 1 mM amiloride (to 22%) and was absent if extracellular Na+ was substituted by Cs+. Elevating temperature to 38°C increased I ACID, whereas temperatures >40°C profoundly inhibited it (by 82 ± 2%; n = 42). The inhibition was long-lasting (>30 s) but fully reversible. Phorbol ester myristate acetate (PMA, 1 μM) and forskolin (1 μM) inhibited I ACID to 37 ± 5% ( n = 5) and 78 ± 8% ( n = 4), respectively. It is suggested that I HEAT in frog DRG neurons is carried through capsaicin-insensitive nonselective cation channels distinct from vanilloid receptor in mammals, whereas I ACID is carried through amiloride-sensitive sodium channels that are strongly inhibited by noxious heat, possibly due to activation of the intracellular messenger systems.