Vasotocin-Like Activity in the Plasma of the Euryhaline Frog (Rana Cancrivora) After Transfer From Fresh Water to Saline

Elliott, Annie B.; Chew, Miow-Miow

doi:10.1677/joe.0.0660427

Cited by 8 publications

(2 citation statements)

References 14 publications

(27 reference statements)

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“…It is known that a pro¬ nounced dehydration reduces the neurohypophysial content of 'water balance hormone' in Bufo bufo (Jörgensen, Wingstrand & Rosenkilde, 1956) and Rana pipiens (Levinsky & Sawyer, 1953). Using the same toad bladder bioassay, an increased AVT-like activity was found in the plasma of Rana catesbeiana, Bufo marinus (Bentley, 1969) and Rana cancrivora (Elliott & Chew, 1975) after dehydration and im¬ mersion in a hypertonic saline solution respectively. Using an AVT radioimmunoassay, raised plasma AVT concentrations have been observed in Rana catesbeiana after dehydration or immersion in a hypertonic mannitol solution (Pang, Sawyer & Casals, 1974;Rosenbloom & Fisher, 1974;Sawyer & Pang, 1975;Pang, 1977).…”

Section: Discussionmentioning

confidence: 90%

Volumetric control of arginine vasotocin and mesotocin release in the frog (Rana ridibunda)

Nouwen¹,

Kuhn²

1985

Journal of Endocrinology

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Adult male frogs (Rana ridibunda) were subjected to several volumetric and osmometric stimuli and the influence on circulating concentrations of arginine vasotocin (AVT) and mesotocin was studied by the use of highly specific radioimmunoassays. During progressive blood withdrawal (haemorrhage group) urine flow decreased to zero, whereas no change occurred in the plasma and urine osmolality. Control levels of 34.3 +/- 7.3 pmol AVT/1 gradually increased up to 638.3 +/- 179.1 pmol/1 (P less than 0.001) after a blood loss of up to 50-60% of the blood volume. Plasma mesotocin concentrations also increased from 42.4 +/- 9.2 to 70.8 +/- 12.0 pmol/1 (n = 7). Hypervolaemia, produced by the repeated intravenous injection of isotonic Ringer solution, increased the urine flow and osmolality compared to controls but had no influence on the plasma levels of AVT and mesotocin. Hypernatraemia without volume change profoundly increased the urine osmolality but the urine flow was not affected; the plasma concentrations of AVT and mesotocin remained at the control level. Finally, during a 1-h immobilization stress a pronounced antidiuresis occurred in the presence of a constant plasma and urine osmolality and control plasma levels of AVT and mesotocin. It is concluded that the release of AVT and, to a smaller extent, of mesotocin is under volumetric control.

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Section: Discussionmentioning

confidence: 90%

Volumetric control of arginine vasotocin and mesotocin release in the frog (Rana ridibunda)

Nouwen¹,

Kuhn²

1985

Journal of Endocrinology

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“…The regulatory role of vasotocin in amphibians is shown by a three-to four-fold increase of its plasma titre when the euryhaline frog R cuncrivoru is dehydrated (weight loss 4-10%) by transfer from freshwater to saline (400-600 mOsm/kg NaCl for 3-4 h) (Elliott and Chew, 1975). Vasotocin promotes cutaneous water uptake in a variety of anurans except Xenopus Zuevis (Bentley and Main, 1972;Bentley, 1974) and, on the other hand, increases the permeability to water and urea of the frog urinary bladder (Bentley, 1971).…”

Section: Physiological Functionsmentioning

confidence: 99%

Adaptive evolution of water homeostasis regulation in amphibians: Vasotocin and hydrins

Acher

Chauvet

Rouillé

1997

Biology of the Cell

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Volemia and osmolality homeostasis is ensured in vertebrates through neuroendocrine reflexes, involving an afferent neural branch from baro- and osmo-receptors to hypothalamus and an efferent endocrine branch from secretory neurons to target hydroosmotic cells equipped with receptors and effectors. Whereas the osmoregulatory system in the tadpole comprises three organs, namely gut, kidney and gills, as in freshwater fishes, the adult displays a quaternary strategy with gut, kidney, urinary bladder and skin. In particular, the cutaneous permeability entails a great evaporative water loss when the animal is in the open air, loss that must be compensated by water reabsorption through the nephron and the urinary bladder and mainly by water uptake through the skin. Adaptation occurred at the level of these organs by regulation of their permeability through neurohypophysial hormones. Aside from vasotocin, active on the three organs, all anuran Amphibia possess hydrin 2 (vasotocinyl-Gly), a peptide resulting from a down-regulation of provasotocin processing. Exceptionally Xenopus laevis, a permanent aquatic toad, has hydrin 1 (vasotocinyl-Gly-Lys-Arg) instead of hydrin 2. Hydrins are somewhat more active than vasotocin on water permeation of skin and bladder but are devoid of antidiuretic activity. Adaptive evolution has created, along with the vasotocin-nephron system, preserved in all terrestrial non-mammalian tetrapods, additional functions such as the hydrin-skin and hydrin-bladder rehydration mechanisms. Specific hydrin receptors might exist in the skin and the bladder, different from those of vasotocin in the kidney. It is assumed that the water channel recruitment mechanism, found for vasopressin acting on the collecting duct principal cells in mammals, is also involved when vasotocin and hydrins stimulate their hydroosmotic target cells and that hormone-regulated aquaporin 2-like proteins could be identified in the three osmoregulatory organs of amphibians.

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Adaptation of nitrogen metabolism to hyperosmotic environment in Amphibia

Balinsky

1981

J. Exp. Zool.

130

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A large number of species of Amphibia, both Anura and Urodela, are capable of tolerating a moderately saline environment. Rana cancrivora, Bufo uiridis, and Xenopus laevis are among the most euryhaline frogs so far studied. Rana cancriuora can tolerate undiluted seawater. In a saline environment, Amphibia show raised plasma sodium and chloride and raised intracellular potassium and chloride. In the adults, plasma and tissue urea are elevated, especially in the more euryhaline species. Free amino acids contribute negligibly to plasma osmolarity, but are very important in intracellular fluids. By these various means, the osmotic pressure of body fluids is always maintained at a higher level than that of the surroundings. Larval Amphibia, however, do not make urea; Rana cancriuora tadpoles can live in saltwater, but maintain the osmolarity of their body fluids below that of their surroundings.Adaptive responses to hyperosmolar environment include decreased skin sodium transport, greatly reduced urine flow, and release of posterior pituitary hormones. After the initial response, the release of these hormones declines, and urine flow increases. Accumulation of urea occurs slowly, but this substance plays an increasingly important role as adaptation proceeds. Accumulation is due initially to urea retention, and possibly to greater synthesis due to a high concentration of precursors of the urea cycle. In later stages of adaptation, increased urea synthesis is due to elevated levels of urea cycle enzymes, especially those that appear to have been rate-limiting. Liver glutamate dehydrogenase is also elevated. In animals subjected to pure osmotic stress, in solutions not containing sodium, responses are similar to, but not identical with, those caused by a medium containing sodium chloride.

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Vasotocin-Like Activity in the Plasma of the Euryhaline Frog (Rana Cancrivora) After Transfer From Fresh Water to Saline

Cited by 8 publications

References 14 publications

Volumetric control of arginine vasotocin and mesotocin release in the frog (Rana ridibunda)

Volumetric control of arginine vasotocin and mesotocin release in the frog (Rana ridibunda)

Adaptive evolution of water homeostasis regulation in amphibians: Vasotocin and hydrins

Adaptation of nitrogen metabolism to hyperosmotic environment in Amphibia

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