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目的:研究细胞外信号调节蛋白激酶1/2(extracellular regulated protein kinase 1/2,ERK1/2)信号通路在丙酮酸乙酯(ethyl pyruvate,EP)抗大鼠离体心脏缺血再灌注损伤(ischemia reperfusion injury,IRI)中的作用。方法:采用离体大鼠心脏Langendoff逆行灌注模型,缺血45min,再灌注60min。实验分为3组(每组8只),分别为IRI组、EP(2mmol/L)+IRI组、EP(2mmol/L)+PD98059(ERK1/2阻断剂,20μmol/L)+IRI组。记录各组处理后血流动力学指标,包括:左心室发展压(LVDP)、左心室内压最大变化速率(+dp/dtmax)、心率(HR)、冠脉流量(CF);ELISA法检测冠脉流出液中乳酸脱氢酶(LDH)含量;TTC法测定各组心肌梗死面积(infarct size,MI);Western法检测ERK1/2通路相关分子表达(p-ERK1/2、total-ERK1/2、p-p70S6K、total-p70S6K)。结果:与IRI组相比,EP+IRI组心脏IRI后各项血流动力学指标(LVDP、+dp/dtmax、HR、CF)显著改善,其数值分别为(68.1.4±4.5)mmHg,(1 130±93)mmHg/s,(253.6±6.5)次/min和(9.37±0.65)ml/min(P<0.05),冠脉流出液中LDH显著减少到(55.8±4.3)%(P<0.05),心肌MI显著减少到(57.1±4.8)%(P<0.05),p-ERK1/2和p-p70S6K蛋白表达分别显著增加到(308.90±17.81)%和(375.04±20.60)%(P<0.05)。与EP+IRI组比较,PD98059处理可以显著逆转EP对离体心脏血流动力学(P<0.05)、LDH释放量(P<0.05)和心肌MI(P<0.05)的保护作用,同时可以有效下调p-ERK1/2和p-p70S6K蛋白表达(P<0.05)。结论:EP对大鼠离体心脏IRI损伤有明确的保护作用,该作用与激活ERK1/2通路有关。
AIM: To investigate the effect of extracellular regulated protein kinase 1/2 (ERK1 / 2) signaling pathway on the protective effect of ethyl pyruvate (EP) against ischemia / reperfusion injury in isolated rat hearts ischemia reperfusion injury, IRI). Methods: Langendoff retrograde perfusion model of isolated rat heart was used. The ischemia was 45 min and the reperfusion 60 min. The experiment was divided into 3 groups (8 in each group), which were IRI group, EP (2mmol / L) + IRI group, EP (2mmol / L) + PD98059 (ERK1 / 2 blocker, 20μmol / L) . The hemodynamic indexes including the left ventricular development pressure (LVDP), the maximum rate of change of left ventricular pressure (+ dp / dtmax), heart rate (HR) and coronary flow (CF) (LDH) in coronary effluent; infarct size (MI) was measured by TTC method; expression of ERK1 / 2 pathway-related molecules (p-ERK1 / 2 and total-ERK1 / 2, p-p70S6K, total-p70S6K). Results: Compared with IRI group, the indexes of hemodynamics (LVDP, + dp / dtmax, HR, CF) after IRI in EP + IRI group were significantly improved (68.1.4 ± 4.5 mmHg, LDH in coronary effluent decreased significantly to (55.8 ± 4.3)% (P <0.05) with the mean duration of 1 130 ± 93 mmHg / s, 253.6 ± 6.5 times / min and 9.37 ± 0.65 ml / (P <0.05). The expression of p-ERK1 / 2 and p-p70S6K protein in myocardial MI significantly increased to (308.90 ± 17.81)% and (375.04 ± 20.60)% respectively P <0.05). Compared with EP + IRI group, PD98059 treatment could significantly reverse the protective effects of EP on isolated hemodynamics (P <0.05), LDH release (P <0.05) and myocardial MI (P <0.05) Down-regulated the expressions of p-ERK1 / 2 and p-p70S6K (P <0.05). CONCLUSION: EP has definite protective effect on myocardial IRI injury in rats, which is related to the activation of ERK1 / 2 pathway.