RESUMEN
The aim of this study was to study the possible effects of prolonged treatment with metoprolol and propranolol on vascular reactivity. Normotensive male rats were used and they were divided into three groups. First group, received metoprolol, second group received propranolol and third group served as control. Their aortae were isolated and studied for their reactivity and comparison done between pretreatment preparation and control ones. There was a significant increase in the contractile response to noradrenaline in the aortic rings taken from metoprolol or propranolol treated rats as compared with controls. In contrast, there was nonsignificant difference in contractile response to phenylephrine. The relaxation response to acetylcholine in tonically contracted aortic rings showed significant increase in relaxation of aortic rings taken from metoprolol or propranolol treated rats as compared ith control. Whereas, there was no significant change in the relaxant response to sodium nitroprussid in pretreated aortic preparation compared with the control ones