Fig. 1

Physiological effects of vasopressin. AVP Arginine VasoPressin, AQP2 Aquaporin 2. Vasopressin is synthesized in the hypothalamus and circulates along axons of magnocellular neurons to the post-pituitary gland. After stimulation, vasopressin is released into blood circulation, to 3 receptor subtypes. Binding on V1a receptors induces vascular smooth cell contraction in the periphery and on renal efferent arteriole and platelet aggregation. Vasopressin binding on renal V2 receptors causes aquaporin 2 recruitment, leading to water re-absorption and on extra-renal V2 receptors induces the release of coagulation factors. Binding on V1b receptors induces corticotropic axis stimulation and insulin secretion. During septic shock, vasopressin plasma level is low. Administration of vasopressin or its analogues induces a strong vasoconstriction, leading to an increase in blood pressure, and higher glomerular filtration rate