A role for endogenous prostaglandins in the short‐circuit current responses to osmolal changes in isolated frog skin

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Abstract
Reduction in osmolality of the Ringer solution bathing the morphological inside of frog skin (by lowering the NaCl concentration) caused a significant increase in Na transport as measured by the short-circuit current. Pretreatment of the skin with acetylsalicylic acid (2.5 .times. 10-4 M) abolished the short-circuit current and open-circuit potential responses to osmolal change. The output of prostaglandin[PG]-like material from isolated frog skin was increased by incubating the skin in hypotonic Ringer solution. The cyclic[c]AMP levels of isolated frog skin were also increased by a reduction in the osmolality of the Ringer fluid bathing the skin. PG-like material was released both by the separated epithelial and dermal layers of frog skin and the output from both layers, on a unit wet weight basis, did not differ. The output of PG-like material from the separated layers of the skin was substantially greater than from whole skin. Indomethacin (6 .times. 10-6 M) reduced the output of this material by more than 90% from both layers. The relase of PG-like material from the separated layers of the skin was not altered by a reduction in osmolality of the bathing medium. A reduction in the osmolality of the solution bathing frog skin stimulates PG production. The increased level of PG stimulates transepithelial Na transport by stimulating cAMP accumulation. The response to osmolal change can only occur in intact skin since separation of the epithelial and dermal layers abolished the increase in the release of PG-like material to osmolal change. The site of the increased PG production and the exact nature of the stimulus remain to be determined.