Differential effects of propranolol on heart rate and plasma renin activity in patients treated with minoxidil

Abstract

The relationship between PPC and its effect on minoxidil-induced increases in PHA and heart rate was examined in 9 patients with essential hypertension. Concomitant with the minoxidil-induced depression of mean arterial pressure (30.7 ± 3.5 mm Hg, mean ± SEM), heart rate increased from 79.1 ± 3.0 to 100.4 ± 4.6 BPM, and PHA increased from 1.12 ± 0.28 to 8.58 ± 2.83 nglmllhr. Addition of propranolol to minoxidil caused a decrease in heart rate in proportion to log PPC:~ heart rate = 1.1 -12.8 log PPC (r, 0.59, p < 0.005) The relationship between PPC and the reduction in PHA was more complex. While a maio! reduction in PHA was observed at PPC in the range 20 to 60 nglmllhr, there was no consistent effect on PHA at higher PPC. Therefore, maximum antagonism of adrenergicaUy mediated increases in PHA is produced by much lower concentrations of propranolol than maximum suppression of adrenergically mediated increases in heart rate.

Antihypertensive effect of atenolol alone or combined with chlorthalidone in patients with essential hypertension.

“…It is now widely accepted that propranolol reduces plasma renin activity (Buhler, Laragh, Baer, Darracott-Vaughan & Brunner, 1972;Velasco, O'Malley, Robie, Wells, Israili & McNay, 1974) and a similar effect has been reported for atenolol (Amery, Linjnen, Fagard & Reybrouck, 1977). Furthermore, an action on the central nervous system has been proposed for several ,B-adrenergic receptor blockers (Lewis, Reid, Myers & Dollery, 1973) …”

Minoxidil Therapy in Refractory Hypertension Analysis of 155 Patients

“…This phenom enon cannot be attributed to enhanced sodium retention by the kidney and must be due to an increase in thirst and salt appetite which may be due to the elevation in plasma renin activity known to occur during Minoxidil treatment (13,24,25,28,33,41). Various clinical [1,2] and experimental data suggest that all components o f the renin-angiotensin system (renin-sub strate, renin, angiotensin I and II) can increase thirst and promote drinking even in waterreplete animals [8][9][10][11]23,36], Furthermore, angiotensin either directly or via aldosterone may augment salt appetite [11].…”

“…Propranolol has been found to be very effective in this re gard and indeed the majority (90%) of the 155 patients received propranolol in doses of 20-840 mg/day during the treatment with Minox idil. Propranolol has another beneficial effect in that italso suppresses the Minoxidil-induced renin release [20,28,25,30,41], It should be emphasized that the doses of propranolol that are adequate to keep the heart rate during Minoxidil therapy within the normal range exceed the dose needed to obtain the maximum suppression of plasma renin activity [41], It appears, therefore, that the best drug combination in the treatment of uncontrollable hypertension is Minoxidil, propranolol and furosemide. Or course, the diuretic is not needed in severely oliguric patients and in those treated with dialysis.…”

Effect of propranolol on sympathetic nervous activity in hydrallazine‐ treated hypertensive patients.

“…Vasodilator antihypertensive agents such as hydrallazine or minoxidil both decrease blood pressure in patients with essential hypertension and increase the sympathetic nervous activity manifested by an increase in heart rate, cardiac output, plasma renin activity and urinary catecholamine excretion Velasco, O'Malley, Robie, Wells, Israili & McNay, 1974). For both vasodilators, hydrallazine (Ueda et al, 1970) and minoxidil (O'Malley, Velasco, Wells & McNay, 1975), the increase in plasma renin activity is dependent on: 1) an increase in sympathetic activity and 2) the pre-treatnent values of plasma renin activity.…”