THE PROBLEM OF CLINICAL VASOPRESSIN RESISTANCE: IN VITRO STUDIES

Abstract

Dilution of body fluids per se appears to play a major role in the escape from the effects of chronically administered vasopressin. This explanation is supported by in vitro studies with a living membrane; vasopressic action was significantly reduced when the osmolality of the serosal medium was decreased. In potassium depletion there is an associated vasopressin-resistant polyuria; failure to atttain a highly concentrated medullary interstitial fluid because of interference with sodium reabsorption is probably the most important factor. In vitro studies showed that reduced potassium concentrations in the medium had an inhibitory effect on sodium transport but virtually no effect on water reabsorption.