Sympathetic responsiveness and antihypertensive effect of beta-receptor blockade in essential hypertension

The relationship between sympathetic responsiveness and the blood pressure reduction induced by long-term beta-blockade was assessed in patients with essential hypertension. The increase in plasma noradrenaline concentration during physical exercise was used as an index of sympathetic responsiveness. The cardioselective beta-blocker, atenolol, was given to 16 patients with sustained benign essential hypertension for five weeks at a dose of 200 mg/day. Atenolol induced a marked decrease in blood pressure and pulse rate during recumbency, orthostasis and exercise concomitant with a marked increase in plasma noradrenaline concentration (p < 0.0125) and a pronounced decrease in plasma renin concentration (p < 0.01). The ratio of plasma noradrenaline during exercise to the base line concentration correlated significantly with the subsequent decrease in mean arterial blood pressure induced by beta-blockade (r = 0.840; p < 0.001). A less significant correlation was observed between the plasma renin concentration and the subsequent decrease in mean arterial pressure (r = 0.542; p < 0.05). The results obtained indicate that sympathetic responsiveness is an important determinant of blood pressure response to beta-blockade induced by atenolol.