Sodium channels in the apical membrane of human nasal epithelial cells

Objective To study the electrophysiological properties of sodium channels in the apical m embrane of human nasal epithelial cells.Method Nasal epithelial cells of human inferior turbinate from patients with obstructiv e sleep apnea syndrome were cultured in serum free medium on collagen gel-coate d membranes at an air-liquid interface and studied by a patch clamp technique . Results In cell-attached patches, a typical single channel current with a conductance of 21.09 pS and reversal potential of -50.96 were recorded. The permeabilit y ratio P(Na)/P(K) was more than 5.80. In the presence of 10(-4) mm ol/L amiloride in the pipette, the incidence of sodium channels decreased from 26 .67% to 5.13%. This revealed that a population of channels were inhibited by amiloride at a dose of 10(-4) mmol/L. Ca(2+) at dose of 10(-3) m mol/L did not influence the incidence of sodium channels. There was no obvious association between voltage and the open probability of the channels. Conclusions Our results indicate that most Na(+) channels in cell-attached patches of human nasal epithelial cells are amiloride-sensitive and Na(+) selective. Only a few channels are amiloride-insensitive. The channels were not activated by extra cellular Ca(2+) and the open probability followed a voltage-independent manner.