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Hepatic and renal and renal metabolism, renal excretion, elimination half time 10-20 mins.

Vasopressin (arginine vasopressin, AVP; antidiuretic hormone, ADH) is a nonapeptide hormone formed in the hypothalamus and released from the posterior pituitary. Its primary function in the body is to regulate extracellular fluid volume by affecting renal handling of water; however, it also is a potent vasoconstrictor.

AVP has two principal sites of action: the blood vessels and kidney. AVP constricts arterial blood vessels by binding to V1 receptors, which are coupled to the Gq-protein and the phospholipase C/IP3 signal transduction pathway. Normal physiological concentrations of AVP are below its vasoactive range; however, in hypovolemic shock when AVP release is very high, AVP does contribute to the compensatory increase in systemic vascular resistance. The most important physiological action of AVP (especially during normal physiology) is to increase water reabsorption in the kidneys by increasing water permeability in the collecting duct, thereby permitting the formation of a more concentrated urine. This is the antidiuretic effect of AVP and it acts through vasopressin type 2 (V2) receptors coupled to adenylyl cyclase.

As a vasoconstrictor, one of vasopressin’s primary advantages is its relative inefficacy in the pulmonary circulation as compared to alpha agonists (such as phenylephrine)

Vasopressin Summary

  • Hepatic and renal metabolism
  • Renal excretion (t 1/2 10-20 mins)
  • V1 receptor (G proteins) leads to vasoconstriction
  • V2 receptor (AC) leads to increased water permeability in collecting ducts
  • Ideal vasoconstrictor for patients with pulmonary hypertension