Vasopressin, also known as arginine vasopressin (AVP), antidiuretic hormone (ADH), or argipressin, is a neurohypophysial hormone found in most mammals.Its two primary functions are to retain water in the body and to constrict blood vessels.asopressin is secreted from the posterior pituitary gland in response to reductions in plasma volume, in response to increases in the plasma osmolality, and in response to cholecystokinin (CCK) secreted by the small intestine :