title: Early decrease in secretin-, glucagon-, and isoproterenol-stimulated cardiac adenylate cyclase activity in rats treated with isoproterenol.
abstract: Male Wistar albino rats received three times daily for one to five days 0.25 to 5.0 mg/kg D,L-isoproterenol intraperitoneally. D.L-Isoproterenol injections provoked a time dependent- and dose-related cardiac hypertrophy. With moderate hypertrophy, a selective decrease in secretin-stimulated adenylate cyclase activity occurred. When heart hypertrophy was more pronounced, greater losses in secretin-, as well as in D,L-isoproterenol-, glucagon-, guanine nucleotide-, and fluoride-stimulated enzyme activity developed. Hormone stimulations of adenylate cyclase were more severely, curtailed (60 to 65%) than guanine nucleotide or fluoride stimulations (40 to 45%). The accompanying loss in beta-receptors (35%) was proportionately lower than the loss of D,L-isoproterenol sensitivity of adenylate cyclase. This complex pattern of adenylate cyclase desensitization in heart membranes from animals chronically treated with D,L-isoproterenol is reminiscent of that observed in heart membranes from spontaneously hypertensive rats.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D006332:Cardiomegaly / Q000139:chemically induced; D005934:Glucagon / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000187:drug effects; D012633:Secretin / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D011943:Receptors, Adrenergic, beta; D012633:Secretin; D005934:Glucagon; D000262:Adenylyl Cyclases; D007545:Isoproterenol