Autoregulation of tissue blood flow in essential hypertension

Autoregulation of tissue blood flow is a mechanism by which tissues control their own blood supply. The mechanism is dependent on an intrinsic capacity of tissues to vary their arteriolar resistance in relation to their needs. One view of the nature of the increased peripheral resistance in essential hypertension is that it represents autoregulatory vasoconstriction functioning to hold in check a cardiac output that would otherwise be excessive; in this situation autoregulation would be functioning normally. An alternative view is that the increased peripheral resistance represents the effect of a direct-acting vasoconstrictor substance; in this situation autoregulation would be rendered defective in its vasodilator capacity. A study of autoregulatory vasodilatation in eight subjects with essential hypertension supported an autoregulatory mechanism as the cause of the increased peripheral resistance.