Pressor Effect of Beta-Adrenergic Blockade and Angiotensin II in Nephrectomized Rats

An increase in blood pressure in approximately 11% of patients with essential hypertension was observed by Drayer et al. (1) following short-term therapy with the beta-blocker propranolol. The acute i.v. administration of propranolol in these patients did not decrease cardiac output, and in some of the figures presented a certain amount of increase could be seen (2). This clinical observation is obviously the end result of certain compensatory mechanisms. The readjustment of total peripheral resistance (TPR) to compensate for the decreased cardiac output (2) and an unopposed reactive alpha-sympathetic activity (1) were suggested as explanations for this phenomenon.