Bupivacaine inhibits a small conductance calcium‐activated potassium type 2 channel in human embryonic kidney 293 cells

Figures

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  Fig. 1. Concentration-dependent inhibitory effects of bupivacaine, ropivacaine, and lidocaine on SK2 currents. a The SK2 current was inhibited by local anesthetics and apamin in an SK2 cell. b, c, and d Dose-dependent effects of bupivacaine in terms of inhibiting SK2 currents (0 mV) were fitted to the Hill equation to obtain the IC50 value of bupivacaine, ropivacaine, and lidocaine, respectively. The equation was Y = Bottom + (Top − Bottom)/(1 + 10((LogIC50-X)*HillSlope)). The pipette solution contained 1μM free calcium

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  Fig. 2. Inhibitory effect of bupivacaine on SK2 currents was reversible (n = 7 for each concentration).SK2 currents (0 mV) obtained at baseline and in inhibition and washout phases with exposure to 1μM, 10μM, and 100μM bupivacaine, respectively. Baseline: perfusion with Tyrode’s solution. Inhibition: perfusion with Tyrode’s solution containing bupivacaine. Washout: replacement of bupivacaine-containing Tyrode’s solution with normal Tyrode’s solution. Normalization inhibition was calculated as (Currentbaseline− Currentinhibition)/Currentbaseline. The intrapipette free calcium concentration was 1μM. *P < 0.05, compared with the baseline value

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  Fig. 3. Effect of calcium concentration on the inhibitory effect of bupivacaine. a SK2 currents obtained at 0 mV in the presence of different concentrations of free calcium. b Degree of inhibition of SK2 currents (0 mV) by 10μM bupivacaine when the pipette solution contained different concentrations of free calcium. Baseline: perfusion with Tyrode’s solution. Inhibition: perfusion with Tyrode’s solution containing bupivacaine. Washout: replacement of bupivacaine-containing Tyrode’s solution with normal Tyrode’s solution. Normalization inhibition was calculated as (Currentbaseline − Currentinhibition)/Currentbaseline. *P < 0.05, between 0.25μM group and 0.5μM group, #P < 0.05, between 0.5μM group and 1.0μM group. @P < 0.05, between inhibition value and baseline value