title: Studies on the mechanism of inhibition of hepatic cAMP accumulation by vasopressin.
abstract: Vasopressin elicited a dose-dependent inhibition of glucagon-induced cAMP accumulation in isolated hepatocytes. This response was not diminished by incubation of cells with the calmodulin antagonists trifluoperazine or chlorpromazine and was only slightly reduced in Ca2+-depleted hepatocytes. Half-maximal inhibition of cAMP accumulation occurred at 8 X 10(-11) M vasopressin, a dose which does not increase cytosolic Ca2+ in hepatocytes. Direct activation of adenylate cyclase by forskolin was significantly inhibited by vasopressin in Ca2+-depleted cells. It is concluded that inhibition of hormone-induced cAMP accumulation by vasopressin in liver is not dependent on cellular Ca2+ mobilisation but may involve direct inhibition of adenylate cyclase.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002746:Chlorpromazine / Q000494:pharmacology; D005576:Colforsin; D000242:Cyclic AMP / Q000378:metabolism*; D004224:Diterpenes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005934:Glucagon / Q000037:antagonists & inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D014268:Trifluoperazine / Q000494:pharmacology; D014667:Vasopressins / Q000494:pharmacology*
chemical_list: D002147:Calmodulin; D004224:Diterpenes; D014667:Vasopressins; D005576:Colforsin; D014268:Trifluoperazine; D005934:Glucagon; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D002118:Calcium; D002746:Chlorpromazine