At supraphysiological plasma concentrations, vasopressin contracts smooth muscle, resulting in pressor activity. Again at high concentrations, it activates liver glycogen phosphorylase to convert glycogen to glucose. Lipolysis is also increased. The secretion of vasopressin into the portal circulation of the hypothalamopituitary region, together with the secretion of corticotrophin-releasing factor from the median eminence, controls the release of adrenocorticotrophic hormone (ACTH) from the anterior pituitary gland. Recent studies suggest that intracerebral vasopressin may modify behaviour and improve memory in animals.
