Determination of Na +/Cl −, Na +/HCO 3− and Na +/K +/2Cl − co-transporter activity in corneal endothelial cell plasma membrane vesicles

Abstract

Corneal endothelial cell derived plasma membrane vesicles were used to investigate the presence of Na +/Cl −, Na +/HCO 3 − and Na +/K +/2Cl − co-transporter activity in the plasma membranes of these cells. Na +/H + exchange was blocked by the presence of 1 mM amiloride in all determinations. The rate of accumulation of Na + in the presence of chloride or bicarbonate was not significantly different from its accumulation in the presence of acetate, thiocyanate or gluconate. The addition of K + to Na + plus Cl − did not stimulate Na + accumulation into the vesicles. The present work provides no evidence for Na +/K +/2Cl −, Na +/Cl − or Na +/HCO 3 − co-transport in corneal endothelial cell plasma membrane vesicles.