IONIC SELECTIVITY OF VOLUME-SENSITIVE CURRENTS IN HUMAN EPITHELIAL-CELLS

The ion selectivity of swelling-activated Cl- currents has been investigated in three different human epithelial cell lines, two derived from the airway epithelium (9HTEo- and CFNPE9o-) and one from a colon carcinoma (T84). The relative permeability of volume-sensitive currents with respect to Cl- is: I- (1.19) greater than NO3- (1.07) approximately Br-(1.05) greater than Cl-(1.0) greater than F-(0.5) approximately HCO3-(0.48) greater than isethionate(0.28) greater than aspartate (0.14) approximately gluconate(0.13) approximately SO4(2-)(0.12). This type of ion selectivity is similar to that described for depolarization-activated outwardly rectifying Cl- channels found in epithelial cells