Role of sodium intake in the antihypertensive effect of propranolol.

Twelve hypertensive patients had measurements of body weight, blood pressure, plasma renin activity, and plasma volume during periods of normal sodium intake and acute sodium depletion. After receiving propranolol orally for four to 14 weeks, repeat measurements were obtained under identical conditions of sodium intake. During normal sodium intake, propranolol therapy was associated with a decrease in plasma renin activity, a variable tendency to an increase in body weight and plasma volume, and a decrease in mean arterial pressure of 5 mm Hg (NS). During sodium restriction, blood pressure was decreased significantly from that observed during normal sodium intake and propranolol added a further significant decrease of 8 mm Hg (P less than .01). Blood pressure reductions obtained with sodium depletion and acute diuretic therapy were approximately the same with or without propranolol. The increase in plasma renin activity expected with sodium depletion and diuretic therapy was not blunted by propranolol.