Alonso C E, Gamundi S S, Castillo G, Orce G, Coviello A
Departamento de Fisiología, INSIBIO, San Miguel de Tucumán, Argentina.
Comp Biochem Physiol C Pharmacol Toxicol Endocrinol. 1995 Mar;110(3):321-7. doi: 10.1016/0742-8413(94)00089-s.
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.
