Blood pressure, renin activity and heart rate changes during propranolol therapy of hypertension.

To investigate the importance of plasma renin activity in determining the antihypertensive action of propranolol and of heart rate in guiding propranolol therapy, the effect of a graded oral dose of propranolol on blood pressure, plasma renin and heart rate was studied in 24 men with essential hypertension and differing initial levels of renin activity. Although plasma renin decreased substantially in patients with normal and high renin levels tasking a small dose of propranolol (40 mg/day), blood pressure was unchanged in the normal renin group, and a small decrease in systolic pressure alone was noted in those with high plasma levels of renin. Patients with low renin levels had no reduction in blood pressure with small doses of propranolol, but as a group they responded well to a dose of 320 mg/day. Standing heart rate decreased maximally at plasma propranolol concentrations greater than 25 ng/ml, and did not exceed 72 beats/min with plasma concentrations above that level. Overall, the observed responses for plasma renin and heart were more pronounced at lower plasma propranolol concentrations than those for blood pressure.