WHOLE-CELL K+ CURRENTS IN ISOLATED RABBIT CORNEAL EPITHELIAL-CELLS

Membrane currents were recorded from enzymatically isolated cells from basal layers of rabbit corneal epithelium by the whole-cell clamp technique. Pipettes contained 140.4 mm KCl and extracellular K+ concentration was varied. The membrane currents on step voltage changes were rectangular currents with some fluctuations. The fluctuations disappeared near the zero-current potential. The reversal potential in normal Tyrode's solution with 5.4 mm K+ was -57.8 +/- 6.2 mV (mean +/-S.D., n = 10). Increasing [K+]. from 5.4 to 140.4 mm shifted the reversal potentials in the positive direction with a slope of 41.0 mV/decade. Concomitant depolarization of the resting potential was observed on increasing [K+]o. The whole-cell currents were blocked by Cs+ or Ba2+. These suggest that the major current component in the corneal epithelial cells is K+.