Effect of Propranolol on Baroreflex Control of Heart Rate in Young Patients with Essential Hypertension

Abstract

The effect of propranolol on baroreflex control of heart rate was studied in 12 young patients with essential hypertension and was compared with that of 12 age-matched normotensive subjects. Resting heart rate and cardiac index in patients with essential hypertension were significantly higher than those of con trol subjects (p < 0.001, p < 0.01, respectively). The reduction of heart rate and cardiac index after propranolol were significantly greater in paients with essen tial hypertension than in control subjects (p<0.01, p<0.05, respectively). In the control state, the baroreflex slope in young patients with essential hyperten sion was significantly less than that of control subjects (p < 0.01). After pro pranolol, the baroreflex slope was significantly increased in control subjects (p < 0.01), but remained unchanged in patients with essential hypertension. These results suggest, first that the antihypertensive action of propranolol must be due to a mechanism other than the augmented baroreflex function and, sec ond that increased β-adrenergic activity is not a factor contributing to impaired baroreflex function in young patients with essential hypertension.