<prompt> Aquaporin channel mediated through ADHGLUTAquaporin 1Aquaporin 2Aquaporin 3  <response>: 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:- Ganongs Review of Medical Physiology 25th ed; pg num:- 696 