Effects of NEM (5 mM) and CO (30 μM) on single K_Ca channels recorded from inside-out membrane patches held at a membrane potential of –30 mV. (a) Original K_Ca current traces recorded in the absence and then the presence of NEM and CO, consecutively, in the same patch. The dashed lines beside the current traces denote the close state of the channels. (b) NEM decreased the P_o of single K_Ca channels. However, the presence of NEM did not block CO-induced modification of single K_Ca channels. n = 6 from two batches of cell preparations.