牛磺酸镁对缺氧/复氧致大鼠心室肌细胞钠离子通道异常的影响

Effects of taurine-magnesium coordination compound on abnormal sodium channel induced by hypoxia-reoxygenation in rat ventricular myocytes

目的观察牛磺酸镁配合物(taurine-magnesium coordination compound,TMCC)对缺氧/复氧损伤所导致的大鼠心肌细胞异常钠通道电流的影响。方法采用Langendorff逆行主动脉灌流酶溶液消化法,急性分离大鼠单个心肌细胞,以缺氧钠外液模拟缺氧15 min后,给予有氧钠外液5 min制备缺氧/复氧模型。应用全细胞膜片钳技术,在电压钳模式下,以胺碘酮为阳性对照药,记录不同浓度TMCC对正常细胞和缺氧复氧模型细胞钠离子通道电流INa的影响。结果与正常对照组INa峰值(56.89±2.07)pA/pF相比,缺氧/复氧使大鼠心室肌细胞INa峰值减小至(35.05±1.52)pA/pF(n=6,P<0.01),I-V曲线上移。TMCC(100、200、400μmol·L-1)可使减小的电流呈浓度依赖性增加,分别恢复至(35.78±1.95)pA/pF(n=6,P>0.05)、(41.52±0.86)pA/pF(n=6,P<0.01)、(48.34±0.99)pA/pF(n=6,P<0.01),24.24μmol·L-1胺碘酮使其恢复为(39.44±1.24)pA/pF(n=6,P<0.01)。TMCC和胺碘酮均能使上移的I-V曲线下移。此外,TMCC和胺碘酮还可恢复因缺氧/复氧右移的失活曲线,使失活减慢,但对激活的影响并不明显。结论 TMCC(200、400μmol·L-1)通过抑制钠通道的失活过程以恢复缺氧/复氧损伤引起的INa峰值减小,使上移的I-V曲线下移,提示该作用可能是TMCC抗缺血性心律失常的机制之一。

Aim To investigate the antiarrhythmic mechanism of taurine-magnesium coordination com-pound on abnormal sodium current channel （ INa ） in-duced by hypoxia-reoxygenation in ventricular myocytes of rats. Methods Single ventricular myocytes were i-solated from each rat heart using enzymatic dissociation through Langendorff retrograde aortic perfusion. Whole-cell patch clamp was applied in voltage clamp mode to record INa both in normal ventricular myocytes and single ventricular myocytes of arrhythmia induced by hypoxia-reoxygenation. Results The peak density of INa was changed from （ 56. 89 ± 2. 07 ） pA/pF to （35. 05 ± 1. 52） pA/pF（ n=6, P 〈 0. 01 vs control） by hypoxia-reoxygenation with the INa I-V curve shifting upward. TMCC（200, 400 μmol·L-1）was able to re-store the reduction caused by H/R to （35. 78 ± 1. 95） pA/pF, （41. 52 ± 0. 86） pA/pF, （n=6,P 〈 0. 01） and （48. 34 ± 0. 99） pA/pF（n=6,P〈 0. 01） respec-tively, but not at 100 μmol·L-1（n=6, P〉0. 05）, in a concentration-dependent manner, while amioda-rone restored it to （39. 44 ± 1. 24） pA/pF （n=6,P〈 0. 01 ） . Both high concentration of TMCC and amioda-rone could shift the I-V curve downward. In addition, TMCC and amiodarone could restore the INa inactivation curve and slow down its inactivation, whereas the acti-vation curves showed no significant differences among groups. Conclusion TMCC（200,400 μmol·L-1） could restore the H/R induced INa reduction and shift the I-V curve downward by inhibiting steady-state inac-tivation, which is suggested to be one of the mecha-nisms of the antiarrhythmic effects of TMCC in hypoxia-reoxygenation model.