Vasopressin acts by:: (A) Water transpo across collecting duct, (B) Water absorption at medullary ducts, (C) Water secretion at loop of Henle, (D) Water transpo at PCT
Answer is A. A i.e. Water transpo across collecting ductVasopressin acts by increasing permeability of collecting ductsQ. to water. The key to the action of vasopressin on collecting duct is aquaporin -2 . The overall effect is retention of water in excess of solute which results in decrease effective osmotic pressure