Action of ouabain on sodium transport in the toad urinary bladder

Abstract

The short-circuit current and transbladder potential difference associated with active ion transport across the toad bladder were depressed by addition of ouabain to the medium bathing the serosal surface of the bladder. On the contrary, the passive movement of chloride across the bladder was unaffected. Ouabain markedly in hibited the flux of sodium from the cells to the serosal solution across the basal surface of the epithelial cells. The sodium flux from the cells to the mucosal solution across the apical cell membrane showed an increase whereas the sodium fluxes from the mucosal and serosal solutions into the cells and the sodium transport pool remained unchanged in the presence of the glycoside. The results indicate that the action of ouabain on toad bladder is a consequence of a primary inhibition of the active transport mechanism at the basal barrier of the epithelial cells.