Transepithelial potential and short-circuit current across the isolated skin ofGillichthys mirabilis (Teleostei: Gobiidae), acclimated to 5% and 100% seawater

Abstract

Skin samples taken from the scaleless and well-vascularized area of the lower jaw were used in a modified Ussing chamber to test for electrogenic ion transport. In the absence of electrochemical gradients the skin developed a transepithelial potential (TEP) of 10–30 mV, serosa-positive, with a short-circuit current (SCC) of 13.7±3 or 20.8±7 μamp/cm2 for fish acclimated to 5% or 100% sea water, respectively. Iodoacetamide +2,4-dinitrophenol, ouabain, or acetazolamide rapidly inhibited the TEP and SCC when perfused on the serosal side, but had little effect when added to the mucosal side. Sodium-, potassium-, or chloride-free Ringer, on both sides, reversibly reduced the TEP and SCC to near zero. The results indicate active ion transport acrossGillichthys skin and suggest a functional chloride excreting pump in the skin of seawater-adapted fish.