<prompt> The site of action of vasopressin isAscending limb of loop of HenleDescending limb of loop of HenleDistal tubuleProximal tubule  <response>: Vasopressin ADH Increasing the water permeability of distal tubule and collecting duct cells in the kidney, thus allowing water reabsorption and excretion of more concentrated urine. Ref: Ganongs Review of Medical Physiology; 24th edition; page no: 698 