EFFECTS OF ETHACRYNIC ACID ON ELECTROLYTE AND WATER CONTENTS OF RAT RENAL CORTICAL SLICES

1. 1. Slices of rat renal cortex were leached anaerobically at 0.5° and reincubated at 25° in oxygenated medium containing ethacrynic acid. In 0.5 mM ethacrynic acid slices showed definite, and in 0.75 mM probable, initial recovery in volume during reincubation which was subsequently not maintained. Slices reincubated in 1 mM ethacrynic acid continued to swell without significant initial recovery. 2. 2. Slices reincubated in oxygenated medium with 1 mM ethacrynic acid and slices reincubated anaerobically with 1 mM ethacrynic acid and 10 mM iodoacetate became significantly more swollen than slices reincubated anaerobically with 10 mM iodoacetate alone. 3. 3. O2 consumption of slices incubated at 25° in medium containing ethacrynic acid was markedly depressed and slices swelled. The presence of 10 mM ouabain together with 1 mM ethacrynic acid did not decrease O2 consumption further though it resulted in a lower tissue K+ content. 4. 4. Slices leached anaerobically and reincubated in oxygenated medium with 0.01 mM 2,4-dinitrophenol showed initial recovery in volume which was not maintained. Slices leached and reincubated with 0.1 mM and 1 mM 2,4-dinitrophenol showed no appreciable recovery. 5. 5. The results were consistent with the possibility that ethacrynic acid inhibits cellular metabolism, rather than with the suggestion that ethacrynic acid specifically inhibits a mechanism primarily concerned in the regulation of cellular volume. 6. 6. Although ethacrynic acid probably increased the permeability of cellular membranes to K+ it was not possible to decide whether it also specifically interfered with linked Na+-K+ transport or, instead, produced loss of tissue K+ as a result of inhibition of metabolism. © 1969.