Haemodynamic effects of beta-adrenorecptor blockers in hypertension

The haemodynamic effect pattern of beta-blockers in hypertension is discussed. The time curve of the antihypertensive effect differs from that of cardiac beta-blockade. The antihypertensive effect is characterized by a slower onset at the start of treatment and a more gradual disappearance when therapy is withdrawn. It appears that the crucial effect of beta-blockers in hypertension is a gradually developing reduction in total peripheral vascular resistance. The mechanism of this apparent vasodilator action is unknown. Various possible factors involved are mentioned. One is a reduced efficiency of transmitter release from the peripheral adrenergic neuron. Such an action may contribute to the antihypertensive effect, as judged by results of animal experiments described.