[The beta-adrenergic receptor and adenylate cyclase of rat reticulocytes as a test system for screening pharmacologic preparations]

The effect of cardio- and neurotropic drugs was studied on beta 2-adrenergic receptors and coupled adenylate cyclase (AC) from rat reticulocytes. Trifluperazine, chlorpromazine, levomepromazine, metaphenazine, haloperidol, (+) and (-) isomers of butaclamol, as well as imipramine, vinblastine and verapamil, at a concentration of 10(-4) M failed to influence AC stimulation by isoproterenol. Thioproperazine and trifluperidol inhibited isoproterenol-stimulated AC with Ki = 4.0.10(-5) M and Ki = 4.5.10(-5) M, respectively. This inhibitory effect was due to the direct action of thioproperazine and trifluperidol on the beta-adrenergic receptors, since this drugs displace the receptor-bound (3H) dihydroalprenolol with Ki = 5.10(-6) M and 9.10(-6) M, respectively. The results obtained suggest that adrenolytic effect of trifluperidol and thioproperazine might play a significant role in their side effects.