Role of Ca2+ and prostaglandin in regulation of active Na+ transport in frog skin.

1. The role of prostaglandins and intracellular Ca2+ in regulation of active transepithelial sodium transport in frog skin were studied by examinations of effects of the calcium ionophore A23187 on short-circuit current (SCC) and intracellular voltage. 2. A23187 and arachidonic acid induced a marked increase in both SCC and prostaglandin E2 synthesis. 3. In indomethacin treated skins A23187 did not stimulate but on the contrary inhibited the basal SCC. 4. The A23187-induced increase in SCC was associated with a decrease in the fractional resistance of the apical membrane and a depolarization of the cells. 5. In skins pretreated with indomethacin, the A23187 induced inhibition of SCC coincided with a slight hyperpolarization of the cellular potential and an increase in fractional resistance of the apical membrane.