Vasopressin: Molecular Mechanisms of Its Antidiuretic Effect

The body’s water balance is regulated by the neurohypophyseal hormone vasopressin. Numerous investigators have identified a significant role for aquaporins – water channels in cell membranes – in regulating permeability. This review presents recent published data on the molecular mechanisms underlying the short-term control by vasopressin of the water permeability of renal tubules via displacement of aquaporin 2 from vesicles to the apical membranes of principal cells and the long-term action of the hormone on gene expression and the levels of aquaporins types 2, 3, and 4 in epithelial cells. Data on the actions of modulators of the hydroosmotic effect of vasopressin (prostaglandin E 2 , bradykinin, dopamine, and endothelin 1) are summarized. Changes in the expression or displacement of aquaporin 2 are of particular importance in pathology in conditions of impairments to the concentrating function of the kidneys.