Fig. 5. Effects of bupivacaine, levobupivacaine, and ropivacaine on the channel activities of the truncated isoform of inwardly rectifying K+channel 6.2 (Kir6.2ΔC36) in the excised inside-out configurations. Kir6.2ΔC36 can form functional adenosine triphosphate–sensitive K+channels in the absence of sulfonylurea receptor molecules. ( A ) Single-channel currents recorded from COS-7 cells transfected with cDNA encoding Kir6.2ΔC36 in the excised inside-out configuration. Representative examples of Kir6.2ΔC36 currents obtained before and after the application of adenosine triphosphate (ATP; 1 mm) and bupivacaine (1 mm). Membrane potentials were clamped at −60 mV. The periods of drug treatment are indicated with horizontal bars .( B ) Concentration-dependent effects of bupivacaine ( diamond ), levobupivacaine ( open circle ), and ropivacaine ( solid circle ) on the activities of Kir6.2ΔC36 channels. Each point constitutes measurements from 12–16 patches (mean ± SD). * P < 0.05 versus baseline (before drug) .