Glutathione potentiates cloned rat brain large conductance Ca(2+)-activated K(+) channels (rSlo)

We have investigated the modulation of a cloned rat brain alpha-subunit of large conductance Ca(2+)-activated K(+) channels (rSlo K(+) channels) by glutathione (GSH), a physiological sulfhydryl-specific reducing reagent. The application of GSH to the intracellular side of excised inside-out macroscopic patches of rslo-transfected HEK293 cells reversibly activated the currents. The activation rate constants of the current were increased while the deactivation rate constants were decreased by GSH at all voltages tested without any change in the voltage dependence of the rate constants. GSH induced a leftward shift of the steady state conductance-voltage relationship curve of the current with no change in the slope of the curve. These results suggest that modulation by GSH may constitute an important regulatory mechanism of neuronal large conductance Ca(2+)-activated K(+) channels.