Beeinflussung der hämodynamischen Streßreaktion bei Hypertonikern durch eine kombinierte α und β-Blockade mit Labetalol*

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Abstract
The hemodynamic reaction to an acute emotional stress was tested in 9 patients with essential and 11 with renal hypertension after an i.v. 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 prelabetalol 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 was 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 was reduced by labetalol, remained uninfluenced by stress: emotional hyperemia was much less.