Hemodynamic and endocrine changes associated with hypotensive action of amosulalol in essential hypertension

To clarify the hemodynamic and endocrine mechanisms of the hypotensive effect of amosulalol, an alpha- and beta-adrenoceptor antagonist, 19 patients with essential hypertension received amosulalol (20-80 mg/day; average 48.4 mg/day) for 16 weeks. Mean blood pressure (MBP) was significantly decreased (105 +/- 1 vs. 120 +/- 1 mm Hg, p less than 0.001), associated with a decrement in heart rate (HR). Although both cardiac index (CI, 3.68 +/- 0.09 vs. 3.91 +/- 0.09 L/min/m2, p less than 0.001) and total peripheral resistance index (TPRI, 2,271 +/- 78 vs. 2,441 +/- 79 dynes.s.cm-5.m2, p less than 0.001) were reduced, changes in TPRI positively correlated with those of MBP (r = 0.9155, p less than 0.001) but the change in CI did not (r = 0.3568, NS). Plasma renin activity (PRA, 0.55 +/- 0.09 vs. 0.95 +/- 0.14 ng/ml/h, p less than 0.05) and aldosterone concentration (4.6 +/- 0.4 vs. 8.6 +/- 0.5 ng/dl, p less than 0.001) were also decreased with amosulalol. Thus, the hypotensive effect of amosulalol may be due mainly to vasodilation by alpha 1-blocking action. In addition, this hypotensive effect may be facilitated by either beta-blocking action such as decreased cardiac output (CO), with suppression of reflex tachycardia or of the renin-angiotensin-aldosterone system.