Regulation of the adenylate cyclase system by catecholamines in the rat prostate.

Tolerance to catecholamines in the beta-adrenergic and dopaminergic receptor-adenylate cyclase system from the rat prostatic membrane has been studied. Preincubation of the tissue with isoproterenol produced not only a decrease in beta-adrenergic receptors and its sensitive adenylate cyclase activity, but also a reduction in dopaminergic response. Similarly, exposure to dopamine resulted in a decline both of isoproterenol- and dopamine-stimulated adenylate cyclase activity. A beta adrenergic antagonist, propranolol, exclusively blocked desensitization in the beta-adrenergic and dopaminergic adenylate cyclase system caused by isoproterenol, while dopamine-induced refractoriness was prevented by a dopaminergic antagonist, haloperidol. These results suggest that desensitization of the beta-adrenergic and dopaminergic adenylate cyclase system begins on receptor-occupation by its specific agonist.