Adenylate Cyclase Activity in Rat Myocardium Following Chronic Infusions of Angiotensin II and Epinephrine

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Abstract
Adrenergic receptor response coupling pathways differ in hypertrophied hearts in different models of hypertension. To mimic this, chronic s.c., infusions of epinephrine (80 nmol/h for up to 13 days) and angiotensin II (AII) (4.3 nmol/h for up to 4 wk) were given. Myocardial-, basal-, isoproterenol-, glucagon-, forskolin- and Gpp(NH)p-stimulated adenylate cyclase were measured. No changes in enzyme activity followed AII infusion, although myocardial hypertrophy was significant. After epinephrine infusion for 6 days, there was a decrease in isoproterenol stimulated enzyme. After 13 days of infusion basal and stimulated cyclase activity was reduced. In hearts from different models of experimental hypertension associated with cardiac hypertrophy, there are different biochemical alterations in the .beta.-adrenergic receptor response coupling mechanism.