Immediate effects of labetalol on central, splanchnic-hepatic, and forearm haemodynamics during pleasant emotional stress in hypertensive patients.

The effects of intravenous administration of labetalol in a dose of 0.75 mg/kg body weight on central, splanchnic-hepatic and forearm haemodynamics were studied in 8 hypertensive patients resting in the supine position and during pleasant psychic stress induced by practice of a television-game of tennis. In the resting state labetalol caused immediate reduction of arterial blood pressures and of total vascular resistance, whereas heart rate, cardiac output and splanchnic-hepatic and forearm blood flow remained unchanged. After labetalol, the stress-induced increase in heart rate, cardiac output, estimated myocardial oxygen demand and forearm blood flow was significantly reduced, whereas total vascular resistance and splanchnic-hepatic vascular resistance remained unchanged. This is taken to indicate that the alpha-adrenoceptor blocking properties of labetalol may offer haemodynamic advantages as compared to the widely used non-selective beta-adrenoceptor blocking agents in the management of hypertension.