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 E2, 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.