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目的探讨二氮嗪预处理(DPC)对心肌缺血/再灌注损伤保护作用的机制。方法Wistar大鼠26只,建立离体心脏Langendorff灌注模型,随机分成4组,即:①缺血/再灌注组(I/R组,n=10):在心脏平衡灌流30 min后,缺血30 min再灌注K-H液1 h。②二氮嗪预处理组(DPC组,n=10):在心脏平衡灌流10 min后,给予含二氮嗪(100μmol/L)的K-H液灌注5 min,再复灌不含二氮嗪的K-H液5 min后,给予含二氮嗪的K-H液灌注5 min;再复灌不含二氮嗪的K-H液5 min,然后缺血30 min,再灌注K-H液1 h。③空白对照组(n=3):用等量盐水代替二氮嗪,过程同DPC组。④二甲基亚砜组(DMSO组,n=3):用DMSO代替二氮嗪,过程同DPC组。取4组大鼠心尖肌制作冰冻切片和电镜标本。前者用于免疫组化染色检测过氧化物酶体增生激活受体γ协同刺激因子1α(PGC-1α)的表达;后者用于对心肌线粒体进行Flameng评分。结果I/R组、DPC组、空白对照组和DMSO组的PGC-1α平均积分吸光度值(IODA),分别为(3.88±1.72)、(8.40±3.64)、(3.40±2.44)和(3.69±1.92),DPC组与其他组比较PGC-1α的表达明显增高(P<0.05)。Flameng评分:I/R组为(1.78±0.14),DPC组为(0.47±0.10),空白对照组为(1.69±0.23)、DMSO组为(1.72±0.17),DPC组较其他组线粒体的损伤明显减轻(P<0.01)。结论DPC后,心肌中PGC-1α的表达明显增加,线粒体的损伤明显减轻,提示DPC对心肌的保护作用与PGC-1α的高表达有关,PGC-1α可能是一种内源性心肌保护物质。
Objective To investigate the protective effect of diazoxide preconditioning (DPC) on myocardial ischemia / reperfusion injury. Methods Twenty-six Wistar rats were divided into four groups according to Langendorff’s perfusion model: ① ischemia-reperfusion group (I / R group, n = 10) 30 min reperfusion KH solution 1 h. Diazoxide preconditioning group (DPC group, n = 10): KH solution containing diazoxide (100μmol / L) was perfused for 5 min after cardiopulmonary balance infusion for 10 min, then re-dosed without diazoxide After 5 min of KH solution, KH solution containing diazoxide was infused for 5 min. KH solution without diazoxide was reperfused for 5 min. Then ischemia was performed for 30 min and then KH solution was infused for 1 h. ③ blank control group (n = 3): Equivalent saline instead of diazoxide, the same process with the DPC group. ④ dimethyl sulfoxide group (DMSO group, n = 3): DMSO instead of diazoxide, the same process with the DPC group. Four groups of rat apical muscles were used to make frozen section and electron microscope. The former was used to detect the expression of peroxisome proliferator-activated receptor γ co-stimulatory factor 1α (PGC-1α) by immunohistochemistry; the latter was used to perform Flameng score on myocardial mitochondria. Results The mean integral optical density (IODA) of PGC-1α in I / R group, DPC group, blank control group and DMSO group were (3.88 ± 1.72), (8.40 ± 3.64), (3.40 ± 2.44) and 1.92). The expression of PGC-1α in DPC group was significantly higher than that in other groups (P <0.05). Flameng score was (1.78 ± 0.14) in I / R group, (0.47 ± 0.10) in DPC group and (1.69 ± 0.23) in blank control group, and (1.72 ± 0.17) in DMSO group. The mitochondrial damage in DPC group Significantly reduced (P <0.01). Conclusion After DPC, the expression of PGC-1α in myocardium was significantly increased and the damage of mitochondria was significantly reduced, suggesting that the protective effect of DPC on myocardium is related to the high expression of PGC-1α. PGC-1α may be an endogenous protective agent of myocardium.