胆碱纠正三氧化二砷诱导豚鼠心电图QT间期延长的分子生物学机制

Molecular biological mechanisms of choline-modulated arsenic trioxide-induced electrocardiogram QT interval prolongation in guinea pig

目的观察胆碱对三氧化二砷（arsenic trioxide，As2O3）诱导豚鼠心电图QT间期延长的纠正作用，探讨其分子生物学机制。方法40只豚鼠按体质量随机分为5组：0（对照）、0．4、0.8、1．6mg／kg As2O3组和胆碱＋As2O3组（8mg／kg胆碱＋1．6mg／kg As2O3），每组8只，静脉给药后，分别测量6个时间点（0、10、30、60、90、120min）的心电图，观察校正的QT间期（QTc）的变化。6h后，提取心肌组织总RNA，用反转录聚合酶链式反应（RT—PCR）方法观察胆碱对As2O3诱导豚鼠心肌L-型钙通道αIC和钾通道GPERG mRNA表达改变的影响。结果在0．8mg／kg As2O3组，60、90、120min时的QTc（354±22、366±31、368±29）与同时间对照组（325±26、336±26、324±20）比较，差异均有统计学意义（P〈0．05或〈0．01）；90、120min时的QTc与0min时（334±12）比较，差异均有统计学意义（P〈0．05）。在1．6mg／kg As2O3组，10、30、60、90、120min时的QTc（362±33、380±21、382±35、388±39、388±31）与同时间对照组（328±20、324±25、325±26、336±26、324±20）比较，差异均有统计学意义（P〈0．05或〈0．01）；与0min时（329±31）比较，差异均有统计学意义（P〈0．05或〈0．01）。在30、60、90、120min时，胆碱＋As2O3组的QTc（337±17、341±15、344±22、343±19）与1．6mg／kg As2O3组相同时间比较，差异均有统计学意义（P〈0．05或〈0．01）。RT—PCR结果显示1．6mg／kg As2O3组的心肌L-型钙通道αIC mRNA表达量为（1．27±0．14），对照组为（1．02±0．12），组间差异有统计学意义（P〈0．01）；胆碱＋As2O3组的心肌L-型钙通道αIC mRNA表达量为（1．10±0．13），与1．6mg／kg As2O3组比较，差异有统计学意义（P〈0．05）。0-4、0．8、1．6mg/kg As2O3组豚鼠心肌钾通道GPERG mRNA表达量分别为1．29±0．11、1．22±0．12、1．27±0．16，与对照组（1．23±0．08）相比较，差异均无统计学意义（P〉0．05）；胆碱＋As2O3 1．6mg／kg组表达量为I．30±0．14，与1．6mg／kg As2O3组比较，差异无统计学意义（P〉0．05）。结论胆碱可以纠正由As2O3诱导的豚鼠心肌QT间期延长，其机制可能与胆碱调节由As2O3引起的L-型钙通道mRNA表达异常有关。

Objective To observe the therapeutic action of choline on As2O3 induced electrocardiogram （ECG） QT interval prolongation and to further explore molecular biological mechanisms. Methods 40 guinea pigs were divided into 5 groups randomly with 8 rats in each group： control group intravenously injected with saline, experimental group with 0.4, 0.8, 1.6 mg/kg of choline and As2O3 group with 8 mg/kg choline plus 1.6 mg/kg As2O3. After a series of concentration of As2O3 was intravenously given, ECG was monitored at different time（0,10, 30,60,90,120 min）, and corrected QT interval（QTc）was studied. Total RNA was abstracted from the guinea pigs hearts after 6 h, and the effects of choline on altered L-type calcium channel αIC and potassium channel GPERG mRNA expression caused by As2O3 in cardiomyocytes of guinea pig were studied by the method of reverse transcription polymerase chain reaction（RT-PCR）. Results In 0.8 mg/kg As2O3 group, the value of QTc at 60,90 and 120 min respectively being 354 ± 22,366 ± 31 and 368 ± 29 was significantly higher than that of control groups[ （325 ± 26,336 ± 26 and 324 ± 20） at same time] with a significant difference （P 〈 0.05 or 〈 0.01）; the value of QTc at 90 and 120 min was significantly higher than that of 0 min group（334 ± 12）, the difference being statistically significant（P 〈 0.05）. In 1.6 mg/kg As2O3 group, the value of QTe at 10,30,60,90 and 120 min respectively being 362 ± 33,380 ± 21,382 ± 35,388 ± 39 and 388 ± 31 was significantly higher than that of control groups[ （328 ± 20,324 ± 25,325 ± 26,336 ± 26 and 324 ± 20） at same time] with a significant difference （P 〈 0.05 or 〈 0.01）; the value of QTe at 10,30,60,90 and 120 min was significantly higher than that of 0 min group（329 ± 31 ）, the difference being statistically significant （P 〈 0.05）. In choline ＋ As2O3 group, the value of QTe at 30,60,90 and 120 min was 337 ± 17,341 ± 15,344 ± 22 and 343 ± 19, significantly lower than that of 1.6 mg/kg As2O3 group, the difference being statistically significant （P 〈 0.05 or 〈 0.01 ）. The RT-PCR results indicated that the value of L-type calcium channel αIC mRNA expression at the concentration of 1.6 mg/kg As2O3 was 1.27 ±0.14vs 1.02 ± 0.12 of control group（P〈 0.01）, and it was 1.10 ± 0.13 in choline ＋ As2O3 group（P 〈 0.05 vs 1.6 mg/kg As2O3 group）. The value of potassium channel GPERG mRNA expression were 1.29 ± 0.11,1.22 ± 0.12 and 1.27 ± 0.16 at the dose of 0.4,0.8,1.6 mg/kg As2O3（P 〉 0.05 vs 1.23 ± 0.08 of control group）. In choline ＋ As2O3 group, the value was 1.30 ± 0.14 （compared with 1.6 mg/kg As2O3 group, P 〉 0.05）. Conclusions Choline normalizes QTe abnormality during As2O3 application, and modulating changed calcium channel mRNA expression induced by As2O3 may be one of the mechanisms.