[Properties of KATP channels in hippocampal CA1 pyramidal neurons from adult rats]

Properties of KATP channels in acutely dissociated hippocampal CA1 pyramidal neurons of adult rats were studied with inside-out patch-clamp technique. With symmetrical 140 mmol/L K+ on both sides of the excised membrane, the single-channel conductance was approximately 63 pS and the reversal potential was 1.71 mV. These channels had a weak inward rectifying property. Channels' openings interrupted by shorter closed intervals were more frequently observed at negative holding potential than at positive holding potential. However, noticeable voltage dependence was not found in channel open probability. ATP applied at the cytosolic side inhibited channel activity in a concentration-dependent manner with an IC50 of 0.1 mmol/L. Sulphonyluren tolbutamide (1 mmol/L), a specific KATP channel blocker, added to the bath completely suppressed the channel activity, while diazoxide (1 mmol/L), a KATP channel opener, had no apparent effect.