ACTIVE CHLORIDE TRANSPORT BY THE SKIN OF A MARINE TELEOST IS STIMULATED BY UROTENSIN-I AND INHIBITED BY UROTENSIN-II

The caudal neurosecretory peptide, urotensin (U) I, stimulated in vitro short-circuit current (Isc) across skin from the marine teleost Gillichthys mirabilis. UI reversed the previous inhibition of Isc by both epinephrine and UII, and stimulated untreated skins that had low Isc. UII and epinephrine reduced Isc and net Cl- flux by decreasing efflux; a phosphodiesdterase inhibitor, 3-isobutyl-1-methylxanthine, stimulated Isc and Cl- net flux by increasing both unidirectional fluxes. UI apparently can antagonize the effects of UII and epinephrine on active Cl- transport by Cl- secreting cells of marine teleosts.