الفهرس 
PHYSIOLOGY OF VASOPRESSINOnly 14 pages are availabe for public view
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Abstract
Arginine vasopressin (AVP), also known as vasopressin, argipressin or antidiuretic hormone (ADH), It is derived from a preprohormone precursor that is synthesized in the hypothalamus and stored in vesicles at the posterior pituitary to be released into the bloodstream. The vasopressins are peptides consisting of nine amino acids (nonapeptides).
There are three subtypes of vasopressin receptors, V1, V2, and V3, have been identified. V1 receptor is further divided into V1A &V1B. V1 receptors are found on various cells including vascular smooth muscle, and V1 stimulation causes vasoconstriction. Kidney collecting duct cells express V2 receptors, which mediate water retention. V3 receptors are mainly found on cells within the central nervous system, especially in the adenohypophysis; their stimulation modulates corticotropin secretion.
In shock states vasopressin infusion leads to vasoconstriction. low-dose (up to at least 0.03 U/min, and maybe as high as 0.067 U/min) is safe in septic shock. Vasopressin and corticosteroids are both commonly used in septic shock and they both increase responsiveness to endogenous and infused catecho-lamines.
Vasopressin, a nonadrenergic endogenous peptide that induces peripheral, coronary, and renal vasoconstriction via stimulation of the V1 receptors, and through V2 receptor stimulation, vasopressin may induce vasodilation and therefore lessens the end-organ hypoperfusion thought to occur with epinephrine
Vasopressin antagonists produce an aquaresis leading to increased plasma Na+ concentration in the majority of patients with hyponatremia due to SIADH, CHF, and Liver cirrhosis. Conivaptan is a combined V1aR and V2R antagonist and used for treatment of euvolemic hyponatremia.
Vasopressin causes vasoconstriction and arrests the bleeding in 36-100% of patients. The recurrence rate following completion of vasopressin infusion can be as high as 71%; therefore, vasopressin is used to temporize the acute event and to stabilize patients before surgery.