Aquaporin channel mediated through ADH

Vasopressin * Vasopressin - secreted by suprachiasmatic nuclei of hypothalamus and transpoed to posterior pituitary * Biologic half life - 18 min * Vasopressin receptors:- V1A and V1B V1A and V1 B:- * G protein coupled receptor that acts phosphatidylinositol hydrolysis to increase intracellular Ca++ concentration * V1A - mediate vasoconstrictor effect * V1B - also called V3 receptors- specific to anterior pituitary - mediate secretion of ACTH V2 receptor:- * G protein coupled receptor that acts through Gs to increase cAMP * Antidiuretic action * Mechanism of action - inseion of aquaporin 2 into the apical membranes of the principal cells of collecting duct. Factors affecting vasopressin secretion Ref:- Ganong's Review of Medical Physiology 25th ed; pg num:- 696