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目的:研究硫氧还蛋白(Trx)系统对糖尿病(DM)大鼠左室心肌细胞瞬时外向钾电流(Ito)的影响。方法:以链脲菌素(STZ)诱导的DM大鼠模型为DM组,应用全细胞膜片钳方法记录DM组与对照组大鼠心室肌Ito电流;用分光光度计测量氧化还原活性分子含量;采用5,5-二巯基双-2-硝基苯甲酸(DTNB)法评估蛋白质巯基的氧化程度;应用胰岛素对DM大鼠心肌细胞进行体外孵育,观察孵育前后心肌细胞Ito的变化。用TrxR抑制剂金诺芬或13-顺式视黄酸对经胰岛素孵育的大鼠心肌细胞进行处理,观察处理前后心肌细胞Ito的变化。结果:DM组大鼠心肌Trx还原酶-1(TrxR)、谷胱甘肽还原酶(GR)、左心室心肌自由巯基(P-SH)及心肌细胞Ito密度水平均较对照组明显降低(均P<0.05),而Trx及谷氧还蛋白(Grx)较对照组明显升高(均P<0.05);经胰岛素处理4～5h后,DM组Ito密度较处理前显著增加(P<0.05);TrxR抑制剂金诺芬或13-顺式视黄酸均可以显著降低用胰岛素处理的DM大鼠心肌细胞Ito密度(均P<0.05)。结论:DM大鼠心肌Trx系统功能下降,心肌细胞Ito密度显著下降。
Objective: To investigate the effect of thioredoxin (Trx) on transient outward potassium current (Ito) in left ventricular myocytes of diabetic rats. Methods: DM rat model induced by streptozotocin (STZ) was used as DM group. The whole cell patch clamp method was used to record the Ito current of ventricular muscle in DM group and control group. The content of redox active molecules was measured by spectrophotometer. The oxidative degree of thiol groups was evaluated by DTNB assay. The DM rat myocardial cells were incubated with insulin to observe the change of Ito in cardiomyocytes before and after incubation. Rat ventricular cardiomyocytes incubated with insulin were treated with TrxR inhibitor, auranofin or 13-cis retinoic acid, and the changes of Ito in cardiomyocytes before and after treatment were observed. Results: The levels of TrxR, P-SH and Ito in cardiomyocytes in DM group were significantly lower than those in control group (P <0.05), while the levels of Trx and Grx were significantly higher in the DM group than those in the control group (all P <0.05). After 4 to 5 hours of insulin treatment, the Ito density in the DM group was significantly increased (P <0.05) Trinidrosis or 13-cis retinoic acid could decrease the Ito density of insulin-treated DM rat cardiac cells (all P <0.05). Conclusion: The function of Trx system in DM rats decreased and the Ito density in cardiomyocytes decreased significantly.