肾上腺素对布比卡因抑制大鼠心室肌细胞钠电流的影响

目的：研究肾上腺素对较低浓度布比卡因所抑制的大鼠心室肌细胞钠电流（INa）的影响。方法：采用急性酶解分离法获得Sprague-Dawley雄性大鼠心室肌细胞，随机分为2组（n=5），以全细胞膜片钳技术记录INa，观察0.15 μg/mL肾上腺素对40 μmol/L布比卡因和50 μmol/L布比卡因所抑制的INa的影响。结果：40 μmol/L和50 μmol/L布比卡因对大鼠心室肌细胞INa抑制率分别为（50.2%±5.8%）和（62.7%±7.7%），差异有统计学意义（P＜0.05）。当加入0.15 μg/mL肾上腺素后，40 μmol/L布比卡因组抑制率变到（33.7%± 10.2%），差异有统计学意义（P＜0.05）；50 μmol/L布比卡因组抑制率变为（62.1%±7.3%），差异无统计学意义（P＞0.05），肾上腺素对I-V曲线无明显影响。结论：肾上腺素可以部分恢复较低浓度布比卡因所抑制的心室肌细胞INa，但其作用在较高浓度布比卡因中受到限制。

Effect of epinephrine on inhibition of sodium current induced by bupivacaine in ventricular myocytes of rats

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.