Abstract
BackgroundBupivacaine blocks many ion channels in the heart muscle, causing severe cardiotoxicity. Small-conductance calcium-activated potassium type 2 channels (SK2 channels) are widely distributed in the heart cells and are involved in relevant physiological functions. However, whether bupivacaine can inhibit SK2 channels is still unclear. This study investigated the effect of bupivacaine on SK2 channels.MethodsThe SK2 channel gene was transfected into human embryonic kidney 293 cells (HEK-293 cells) with Lipofectamine 2000. The whole-cell patch-clamp technique was used to examine the effect of bupivacaine on SK2 channels. The concentration–response relationship of bupivacaine for inhibiting SK2 currents (0 mV) was fitted to a Hill equation, and the half-maximal inhibitory concentration (IC50) value was determined.ResultsBupivacaine inhibited the SK2 channels reversibly in a dose-dependent manner. The IC50 value of bupivacaine, ropivacaine, and lidocaine on SK2 currents was 16.5, 46.5, and 77.8µM, respectively. The degree of SK2 current inhibition by bupivacaine depended on the intracellular concentration of free calcium.ConclusionsThe results of this study suggested the inhibitory effect of bupivacaine on SK2 channels. Future studies should explore the effects of SK2 on bupivacaine cardiotoxicity.
Highlights
Bupivacaine blocks many ion channels in the heart muscle, causing severe cardiotoxicity
Concentration–response relationship of bupivacaine, ropivacaine, and lidocaine on the inhibition of SK2 currents HEK 293 cells transfected with the SK2 gene produced representative current tracings
Inhibition of SK2 currents with Local anesthetics (LAs) was reversible the study explored whether the inhibitory effect of bupivacaine was reversible
Summary
Bupivacaine blocks many ion channels in the heart muscle, causing severe cardiotoxicity. Smallconductance calcium-activated potassium type 2 channels (SK2 channels) are widely distributed in the heart cells and are involved in relevant physiological functions. Local anesthetics (LAs), such as bupivacaine, ropivacaine, and lidocaine, are often used for regional anesthesia and analgesia. Their cardiotoxicity differs due to their different chemical structures: bupivacaine > ropivacaine > lidocaine. Small-conductance calcium-activated potassium type 2 channels (SK2 channels) are involved in hyperpolarization after the action potential. These channels function in the atria [13], ventricles [13], atrioventricular nodes [14], and Purkinje cells [15], which play important roles in cardiac conduction.
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