THE EFFECT OF ETHACRYNIC ACID ON SODIUM TRANSPORT BY ISOLATED RABBIT ILETJM

¹ Department of Obstetrics and Gynecology and Department of Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania

The addition of ethacrynic acid to the solution bathing the mucosal surface of short-circuited segments of rabbit ileum brings about an initial increase in the short-circuited current that is followed by a rapid decline. Sixty minutes after exposure of the tissue to 1 mM ethacrynic acid, net transmural sodium transport is abolished, and a marked increase in intracellular sodium concentration associated with a decrease in the intracellular potassium concentration is observed. Further, 1 mM ethacrynic acid brings about an increase in the influx of sodium into the epithelium across the brush border and an increase in the rate of pyruvate production by the tissue. These results suggest that ethacrynic acid increases the permeability of the brush border to sodium and inhibits the active sodium transport mechanism located on or near the serosal or lateral membranes of the epithelial cell.