Immediate Hemodynamic Effects of Beta-Adrenergic Blockade with Propranolol in Normotensive and Hypertensive Man

Immediate hemodynamic effects of beta-adrenergic blockade were determined in six normal subjects and 21 hypertensive patients following intravenous administration of propranolol. Arterial pressure was not reduced, but cardiac output fell by approximately 20% in both groups. Nevertheless, beta-adrenergic inhibition seemed to have different effects in the two groups: Propranolol produced a greater inhibition of chronotropic activity in the hypertensive patients, and of stroke volume in the normotensive individuals whose pretreatment heart rate was slower than that of the hypertensives. This difference suggests that chronotropic beta-adrenergic activity may be increased in hypertension but does not explain reduction in arterial pressure following oral treatment with propranolol.