title: Inhibitory effect of sodium ursodeoxycholate on basal and stimulated short-circuit current across the isolated toad skin.
abstract: The effect of sodium ursodeoxycholate (U) on short-circuit current (SCC), an index of basal and stimulated net ion transport across isolated skins of Bufo arenarum toads, was tested. U inhibited basal SCC when added to the epidermal side of the skins. The inhibitory effect was reversible after rinsing the preparation during 60 min. U also inhibited the natriferic response to oxytocin, db-cAMP and theophylline by 82%, 49% and 47%, respectively. Inhibition of SCC by exposure to U was reversed by the polyene antibiotic nystatin. In turn, SCC induced by nystatin in the amiloride-treated skin was insensitive to U and blocked by ouabain, a Na+, K(+)-ATPase inhibitor. These results strongly suggest that the effect of U is exerted at the apical membrane of sodium transporting cells, and rule out the existence of an additional site of inhibitory action of U.
authors.affiliation: Departamento de Fisiología, INSIBIO, San Miguel de Tucumán, Argentina.
authors.forename: C E
authors.initials: CE
authors.lastname: Alonso
authors.forename: S S
authors.initials: SS
authors.lastname: Gamundi
authors.forename: G
authors.initials: G
authors.lastname: Castillo
authors.forename: G
authors.initials: G
authors.lastname: Orce
authors.forename: A
authors.initials: A
authors.lastname: Coviello
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology; D002022:Bufo arenarum; D004347:Drug Interactions; D004817:Epidermis / Q000187:drug effects / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009761:Nystatin / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D010121:Oxytocin / Q000494:pharmacology; D012867:Skin / Q000187:drug effects*; D012879:Skin Physiological Phenomena; D012964:Sodium / Q000652:urine; D013806:Theophylline / Q000494:pharmacology; D014580:Ursodeoxycholic Acid / Q000633:toxicity*
chemical_list: D009761:Nystatin; D010121:Oxytocin; D010042:Ouabain; D003994:Bucladesine; D014580:Ursodeoxycholic Acid; D000584:Amiloride; D012964:Sodium; D013806:Theophylline