Altered hormone sensitivity of adenylate cyclase in myocardial sarcolemma of renal hypertensive rats.

Adenylate cyclase activity was studied in the myocardial sarcolemmal membranes from sham-operated control and renal hypertensive rats (RHR). Basal adenylate cyclase activity was not significantly different in RHR as compared to control rats. The stimulation of adenylate cyclase by adenosine, epinephrine and norepinephrine was diminished in RHR, whereas dopamine-sensitive adenylate cyclase was almost completely abolished. The decreased responsiveness of adenylate cyclase to catecholamines was associated with a decrease in the Vmax. Furthermore, the stimulation of enzyme activity by F- and forskolin was also decreased. The data indicate that, in renal hypertension, the responsiveness of adenylate cyclase to various hormones and to agents (forskolin and F-) which do not act through receptors is impaired.