Vasopressin-induced transfer via light vesicles of receptors and water channels from basolateral to apical membrane of toad bladder.
Toad bladder epithelial cells were homogenized and fractionated by Percoll density-gradient centrifugation. Binding of tritium-labeled vasopressin ([3H]AVP) was measured in surface membranes (SM), microsomes (M), and a 100,000 g (60-min) microsomal supernatant fraction (S). More than two-thirds of the total receptors were in S. Receptors in SM--but not in S--were tightly coupled to G-protein as suggested by inhibition of [3H]AVP binding by GTP. GTP-sensitivity of [3H]AVP binding was not altered by vasotocin (AVT) stimulation, although the distribution of receptors shifted from SM to S. Intact bladders, exposed on the serosal side to 1-desamino, 7-lysine-(4-azidobenzoyl), 8-arginine vasotocin (d7-N3-AVT) in the presence of UV light, exhibited a persistent hydroosmotic response compared to controls stimulated with photoaffinity analog in the dark. Cell fractions from the irradiated bladders showed a reduction in [3H]AVP binding in SM and S. Intact bladders, exposed on the mucosal side to d7-N3-AVT in the presence of UV light (while stimulated from the serosal side with AVP) exhibited a decrease in [3H]AVP binding in SM compared to controls without d7-N3-AVT.(ABSTRACT TRUNCATED AT 250 WORDS)
Eggena
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Department of Physiology and Biophysics, Mount Sinai Medical School, City University of New York, NY 10029.
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D000345:Affinity Labels / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism; D002024:Bufo marinus; D002458:Cell Fractionation; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002499:Centrifugation, Density Gradient; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D019204:GTP-Binding Proteins / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000494:pharmacology; D066298:In Vitro Techniques; D008861:Microsomes / Q000378:metabolism; D011945:Receptors, Angiotensin / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D017483:Receptors, Vasopressin; D014466:Ultraviolet Rays; D001743:Urinary Bladder / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D014668:Vasotocin / Q000378:metabolism / Q000494:pharmacology / Q000031:analogs & derivatives
D000345:Affinity Labels; D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; C034862:vasotocin receptor; C054313:vasotocin, 1-desamino-(4-azidobenzoyl)Lys(7)-Arg(8)-; D001127:Arginine Vasopressin; D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D014668:Vasotocin