<prompt> The site of action of vasopressin antagonist in kidneyMedullary Collecting ductCoical collecting ductProximal convoluted tubuleDistal convoluted tubule  <response>: V2 receptors are located on medullary collecting ducts. drugs acting on V2 receptor antagonists are vaptans like convivaptan and tolvaptan Ref: Goodman Gillman 12th ed pg 707 