Prostaglandin E2-stimulated glandular ion and water secretion in isolated frog skin (Rana esculenta)

Abstract

Prostaglandins are known to stimulate the active sodium absorption in frog skin. In this paper it is shown that prostaglandin E₂ (PGE₂) stimulates an active secretion of Cl⁻, Na⁺, and K⁺ from the skin glands inRana esculenta. The active Cl secretion is enhanced more than the Na and K secretion. Therefore, in skins where the Na absorption is inhibited by amiloride, the addition of PGE₂ results in an increase in the short-circuit current (SCC). The PGE₂-stimulated Cl secretion could be inhibited by the presence of ouabain or furosemide in the basolateral solution or diphenylamine-2-carboxylate in the apical solution. The PGE₂-stimulated Cl secretion was enhanced by the phosphodiesterase inhibitor, theophylline, indicating that the effect of PGE₂ was caused by an increase in the intracellular cAMP level in the gland cells. The calcium ionophore A23187, which increases the PGE₂ synthesis in frog skin, stimulated the glandular Cl secretion. This secretion could be blocked by the prostaglandin synthesis inhibitor indomethacin, indicating that A23187 acts by increasing the prostaglandin synthesis and not by a direct action of Ca²⁺ ionsper se. The net water flow (J _w) and the Cl secretion were measured simultaneously under the conditions outlined above. The stimulation, inhibition, and the time-course of the outward-directedJ _w were similar to the change observed for the Cl secretion. These results show that PGE₂ stimulates a glandular secretion of Cl and water in frog skin, probably by increasing the cAMP level in the gland cells.