RT Journal Article SR Electronic T1 EFFECTS OF BETA ADRENERGIC BLOCKING AGENTS ON PLASMA RENIN ACTIVITY IN THE CONSCIOUS RABBIT JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 234 OP 240 VO 188 IS 1 A1 Michael A. Weber A1 Ian R. Thornell A1 Gordon S. Stokes YR 1974 UL http://jpet.aspetjournals.org/content/188/1/234.abstract AB The effects of propranolol, 1 mg/kg, oxprenolol, 1 mg/kg and prindolol, 0.125 mg/kg, given in separate experiments on blood pressure, heart rate and plasma renin activity (PRA) over a 3-hour period were investigated in three groups of conscious rabbits. Each of the beta blockers caused a significant fall in mean blood pressure, averaging 10 mm Hg. Heart rate fell after propranolol, but increased slightly after either of the other two drugs was given. Administration of propranolol or oxprenolol resulted in a significant fall in PRA to 50% of control values, whereas prindolol produced a progressive rise in PRA to almost 300% of the control value. Blood withdrawn for analysis was replaced by a protein-saline solution for, in control studies, it was shown that this procedure prevented the rise in PRA caused by blood sampling. In further control studies, propranolol, in the dose given, was shown to block isoproterenol-induced tachycardia in the rabbit. The differing effects of prindolol and the other two agents on PRA may reflect differences in their intrinsic sympathomimetic activity. The hypotensive effect of prindolol was clearly not due to suppression of the renin-angiotensin system. In a further group of 10 animals, when blood loss was not replaced by protein-saline, propranolol, 1 mg/kg, still resulted in a fall in PRA. Thus, propranolol lowered PRA both in the presence and absence of uncompensated blood loss. © 1974 by The Williams & Wilkins Company