Prostaglandin E2 enhances the sodium conductance of exocrine glands in isolated frog skin (Rana esculenta)

Abstract

Prostaglandins are known to stimulate the active transepithelial Na+ uptake and the active secretion of Cl- from the glands of isolated frog skin. In the present work the effect of prostaglandin E2 (PGE2) on the glandular Na+ conductance was examined. In order to avoid interference from the Na+ uptake and the glandular Cl- secretion the experiments were carried out on skins where the Cl- secretion was inhibited (the skins were bathed in Cl- Ringer's solution in the presence of furosemide, or in NO3- Ringer's solution), and the active Na+ uptake was blocked by the addition of amiloride. Transepithelial current, water flow and ion fluxes were measured. A negative current was passed across the skins (the skins were clamped at -100 mV, basolateral solution was taken as reference). When PGE2 was added to the skins under these experimental conditions, the current became more negative; this was mainly due to an increase in the Na+ efflux. Together with the increase in Na+ efflux a significant increase of the water secretion was observed. The water secretion was coupled to the efflux of Na+, and when one Na+ was pulled from the basolateral to the apical solution via this pathway 230 molecules of water followed. From the data presented it is suggested that this pathway for Na+ is confined to the exocrine glands.