Sodium channels in the apical membrane of human nasal epithelial cells

Objective To study the electrophysiological properties of sodium channels i n the apical membrane of human nasal epithelial cells. Method Nasal epithelial cells of human inferior turbinate from patients wit h obstructive sleep apnea syndrome were cultured in serum free medium on co llagen gel-coated membranes at an air-liquid interface and studied by a pat ch clamp technique. Results In cell-attached patches, a typical single channel current with a c onductance of 21.09 pS and reversal potential of -50.96 were recorded. The permeability ratio P-Na/P-K was more than 5.80. In the presence of 10(-4) m mol/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 inhi bited by amiloride at a dose of 10(-4) mmol/L. Ca2+ at dose of 10(-3) mmol/ 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 pa tches of human nasal epithelial cells are amiloride-sensitive and Na+ selec tive. Only a few channels are amiloride-insensitive. The channels were not activated by extracellular Ca2+ and the open probability followed a voltage -independent manner.