DETERMINATION OF NA+ CL-, NA+/HCO3- AND NA+/K+/2CL(-) COTRANSPORTER ACTIVITY IN CORNEAL ENDOTHELIAL-CELL PLASMA-MEMBRANE VESICLES/

Corneal endothelial cell derived plasma membrane vesicles were used to investigate the presence of Na+/Cl-, Na+/HCO3- and Na+/K+/2Cl(-) co-t ransporter activity in the plasma membranes of these cells. Na+/H+ exc hange was blocked by the presence of 1 mM amiloride in all determinati ons. The rate of accumulation of Na+ in the presence of chloride or bi carbonate 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+/H CO3- co-transport in corneal endothelial cell plasmamembrane vesicles. (C) 1997 Elsevier Science B.V.