Prostaglandins lack a direct inhibitory action on electrolyte and water transport in the kidney and the erythrocyte.

The possibility of a direct effect of prostaglandins of the E, A, and F series upon renal electrolyte and water transport was assessed using in vitro preparations of rabbit cortical and medullary tubular suspensions as well as cortical renal slices from rat and guinea pig and medullary renal slices from rabbit. Net fluxes of Na, K, C1 and H2O between the intracellular compartment and the extracellular fluid were measured in the presence of PGE1, PGE2, PGA1, PGA2 and PGF2alpha in concentrations ranging from 1 X 10(-5) to 1 X 10(-10)M. No inhibitory action was observed with any of these prostaglandins and in fact a slight stimulation of Na transport was seen under some circumstances. We conclude that the natriuresis which follows in vivo administration of some prostaglandins is not the result of a direct inhibition of Na reabsorption at the contraluminal pump site and is most likely secondary to renal vasodilation. We also studied net and isotopic Na fluxes in human erythrocytes. Na transport was not affected by prostaglandins of the E, A or F series using both normal and high sodium erythrocytes. Our results emphasize the need for caution in extrapolating the effects of prostaglandins upon Na transport from one tissue to another since their actions appear to be tissue-specific.