Role of vasopressin in cardiovascular and blood pressure regulation.

At low concentrations and in physiologic states vasopressin is a potent antidiuretic hormone. Its cardiovascular effects have been more complex and their role in circulatory adjustments to hypovolemia and hypotension difficult to define with precision. Although recognized as a powerful vasoconstrictor, its pressor effect in intact animals, even at high concentrations, is minimal. The reasons for this blunted pressor response have been explored. This report is a review of previously published work from our laboratories which highlights the direct and indirect vasodilator actions of this hormone in animals and humans. The indirect vasodilator effect is caused by inhibition of sympathetic efferents, and facilitation of the baroreflex through a central action of the hormone and its sensitization of arterial baroreceptors as well as cardiac afferents.