Role of vasopressin in cardiovascular regulation.

Although we are just beginning to appreciate the potential role that arginine vasopressin (AVP) could play in the normal regulation of arterial pressure, a number of points appear already relatively well established. There is now little doubt that AVP can exert significant vasoconstrictor actions at physiological plasma concentrations, although in normal states, AVP-induced elevations of total peripheral resistance do not raise arterial pressure because of strong reflex suppression of cardiac output. It is also clear that AVP can be released in sufficient amounts in hypovolemic states to contribute significantly to the normalization of arterial pressure by direct vasoconstriction. The interaction of AVP with autonomic reflex pathways and the enhancement of baroreceptor reflex gain appear to be an important way in which AVP can also contribute to the short-term stabilization of pressure. Finally, the rapid reflex suppression of AVP and the withdrawal of antidiuretic actions in response to volume loading may serve as another mechanism whereby AVP participates in arterial pressure stabilization.