Topic
Toad
About: Toad is a research topic. Over the lifetime, 1624 publications have been published within this topic receiving 28732 citations.
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TL;DR: Results are consistent with the view that the level of free calcium in the granular cell cytosol plays a modulatory role in the control of apical membrane water and sodium permeability by vasopressin, and in the regulation of the basal rate of transepithelial sodium transport.
Abstract: The effects of experimental procedures believed to increase cytosolic calcium on basal and vasopressin-stimulated osmotic water flow and transepithelial sodium transport were examined in the toad u...
21 citations
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TL;DR: Direct evidence for an effect of somatostatin on hormone-modulated epithelial transport in tissues other than the gastrointestinal tract is provided and it is proposed that endogenous som atostatin may function as a local regulator of the cellular action of vasopressin on osmotic water flow.
Abstract: Somatostatin (somatotropin release-inhibiting factor; SRIF) is a tetradecapeptide present in brain, pancreas, gastrointestinal tract, and thyroid that inhibits the secretion or action of several hormones in these tissues. We observed that the toad urinary bladder contains concentrations of endogenous somatostatin (8.0 pg/micrograms of protein) comparable to those found in the mammalian pancreas and gastrointestinal tract. To determine if somatostatin directly alter the action of vasopressinn we studied the effects of this polypeptide on vasopressin-stimulated transport processes in the toad urinary bladder in vitro. Somatostatin produced a dose-dependent, reversible inhibition of vasopressin-stimulated osmotic water flow; it inhibited theophylline-stimulated osmotic water flow but not the water flow stimulated by 8-p-chlorophenylthioadenosine 3',5'-cyclic monophosphate. These data are consistent with an inhibition of both basal and hormone-stimulated adenylate cyclase. Vasopressin-stimulated short circuit current was not inhibited by somatostatin. These studies provide direct evidence for an effect of somatostatin on hormone-modulated epithelial transport in tissues other than the gastrointestinal tract. We propose that endogenous somatostatin may function as a local regulator of the cellular action of vasopressin on osmotic water flow.
21 citations
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21 citations