EFFECTS OF BEVANTOLOL HCL ON IMMOBILIZATION STRESS-INDUCED HYPERTENSION AND CENTRAL BETA-ADRENOCEPTORS IN RATS

Effects of chronic treatment with bevantolol, a beta-adrenoceptor bloc ker, and of repeated immobilization stress on blood pressure, body wei ght, and [H-3]dihydroalprenolol ([H-3]DHA) binding to the cerebral cor tex were examined in rats. Systolic blood pressure increased to approx imately 150 mmHg when stress was applied for 14 days (2 h day-1). This increase was inhibited by chronic treatment with bevantolol (250 mg k g-1 daily). However, bevantolol did not suppress the inhibition of bod y weight gain by stress. The maximum number of [H-3]DHA binding sites (B(max)) in the cerebral cortex was decreased by stress without changi ng the affinity, and the decrease in B(max) mainly reflected the reduc tion of beta1-adrenoceptors. Bevantolol treatment (250 mg kg-1) increa sed the B(max) to 137% and completely inhibited the downregulation of beta-adrenoceptors by stress. These results show that bevantolol can i nhibit both the hypertension and downregulation of the central beta1-a drenoceptors induced by stress.