CHARACTERIZATION OF INWARDLY RECTIFYING POTASSIUM CURRENTS FROM DISSOCIATED RAT TASTE RECEPTOR-CELLS

Inwardly rectifying potassium currents were recorded from taste recept or cells dissociated from the rat tongue with the use of patch-clamp t echniques in the whole cell configuration. These currents displayed st rong inward rectification at potentials negative to the potassium reve rsal potential and little outward current at potentials positive to it . With elevations of external potassium concentration, the slope and c hord conductance increased, activation shifted toward more depolarized potentials, and the reversal potential varied in a predicted Nernst r elationship. These currents were insensitive to 4-aminopyridine and pa rtially blocked by tetraethylammonium. Both barium and cesium gave mor e complete blocks with characteristic relief at more negative potentia ls. Inhibition with barium was more voltage sensitive than with cesium . These currents were unaffected by changes in external sodium. The hi gh conductance at negative membrane potentials suggests these currents may contribute with other conductances to the resting potential of ta ste cells. They may also participate in yet unidentified processes of taste transduction, resulting in the early depolarization of the resti ng potential.