[Hemodynamic effects of labetalol on the humeral artery of the hypertensive patient. A double-blind study versus placebo].

Forearm arterial hemodynamics, including measurements of brachial artery diameter and compliance with pulsed Doppler velocimetry were determined before and after acute administration of labetalol in patients with sustained essential hypertension. Labetalol caused a significant and rapid drop in blood pressure with a decrease in forearm vascular resistance and an increase in brachial blood flow. Brachial artery diameter did not change while arterial compliance significantly increased. The study provided evidence that labetalol caused a shift of the pressure-brachial artery diameter curve toward lower values of blood pressure, indicating a pharmacological effect of alpha and beta blockade on the hypertensive arterial wall.