Abstract：Objective: To determine the effect of epinephrine on inhibition of sodium current (INa) induced by bupivacaine inventricular myocytes of rats. Methods: The ventricular myocytes isolated from Sprague-Dawley rats by acute enzymatic dissociation were randomly divided into two groups (n=5). The whole-cell patch clamp technique was used to record INa in single ventricular myocytes and the effect of 0.15 ug/mL epinephrine inhibition of INa on induced by 40 or 50 μmol/L bupivacaine were observed. Results: The inhibition rates of 40 μmol/L bupivacaine or 50 μmol/L bupivacaine on INa was 50.2%±5.8 % or 62.7%±7.7 % (P<0.05) respectively. After the administration of 0.15 ug/mL epinephrine, the inhibition rates in the 40 μmol/L bupivacaine group changed to be 33.7%±10.2 % (P<0.05), and which was 62.1%±7.3% (P>0.05) in the 50 μmol/L bupivacaine group. Epinephrine did not shift the I-V curve. Conclusion:Epinephrine can reverse inhibition of INa induced by low-concentration bupivacaine. This effect of epinephrine will be limited to a higher level concentration of bupivacaine.
