beta-adrenergic receptor blockade as a therapeutic approach for suppressing the renin-angiotensin-aldosterone system in normotensive and hypertensivesubjects

Although beta-adrenergic-blocking drugs suppress the renin system (RAAS), p lasma angiotensin II (Ang II) responses during beta-blockade have not been defined. This study quantifies the effects of beta-blockade on the RAAS and examines its impact on prorenin processing by measuring changes in the rat io of plasma renin activity (PRA) to total renin'. In normotensive (N = 14) and hypertensive (N = 16) subjects, blood pressure (BP), heart rate, PRA, plasma prorenin, plasma total renin (prorenin + PRA ), ratio of PRA to total renin (%PRA), plasma Ang II, and urinary aldostero ne were measured before and after 1 week of beta-blockade. Plasma renin act ivity, Ang II, and urinary aldosterone levels were similar for normotensive and hypertensive subjects. Plasma renin activity correlated with Ang II. Total renin, which is proport ional to (pro)renin gene expression, was lower in hypertensive subjects and was inversely related to BP. beta-blockade decreased BP and heart rate in both groups, with medium- and high-renin hypertensive subjects responding m ore frequently than those with low renin. beta-Blockade consistently suppre ssed PRA, Ang II, and aldosterone. Total renin was unchanged, thus, %PRA fe ll. These results indicate that beta-blockers suppress plasma angiotensin II le vels, in parallel with the marked reductions in PRA and urinary aldosterone levels in normotensive and hypertensive subjects. The suppression of Ang I I levels was comparable to that produced during angiotensin converting enzy me (ACE) inhibition. However, by reducing prorenin processing to renin, bet a-blockers do not stimulate renin secretion, unlike ACE inhibitors and Ang II receptor antagonists. This unique action of beta-blockers has important implications for the treatment of cardiovascular disease. (C) 1999 American Journal of Hypertension, Ltd.