[The effect of combined alpha and beta blockade with labetalol on the haemodynamics of stress reaction in hypertensives (author's transl)].

The haemodynamic reaction to an acute emotional stress was tested in nine patients with essential and eleven with renal hypertension after an intravenous bolus of labetalol (0.6--1.6 mg/kg body-weight). Labetalol reduced the arteriolar tone at rest. The emotional blood pressure rise was maintained, but started from a lower level due to labetalol and under stress only rose to the pre-labetalol level. The diastolic pressure rose significantly less compared with control values, while systolic and mean blood pressure responses were not uniform. The usual emotional rise in heart rate and cardiac output was clearly diminished by labetalol. Total peripheral vascular resistance, which had been significantly reduced by labetalol, remained unchanged under acute emotional stress. In contrast to untreated hypertensives, venous distensibility and regional blood volume in the lower arm rose significantly on stress while on labetalol medication. Lower arm vascular resistance, which had also been reduced by labetalol, remained uninfluenced by stress: as a result, emotional hyperaemia was much less.