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目的探讨心肌缺血预处理(IPC)对成年和老年大鼠的心功能及心肌组织和血浆中脂联素表达的影响。方法取成年和老年大鼠各85只,将IPC成功的成年和老年大鼠各50只中,随机各取40只为IPC组,另10只再建心肌梗死(M1)模型为IPC-M1组;只穿线不阻断血流的成年和老年大鼠各30只中,随机各取20只作为假手术组,另10只建MI模型为单纯MI组。假手术组及IPC组又分别于IPC后0、6、12和24h 4个时间点观察。将未结扎冠状动脉的成年和老年大鼠各5只作为对照组。用M型超声检测心功能,Masson’s Trichrome染色,测量MI面积,免疫组织化学法和RT-PCR法测心肌组织脂联素蛋白和mRNA的表达,用ELISA法检测血浆脂联素含量。结果老年大鼠IPC-MI组存活率显著低于单纯MI组和对照组(P<0.05),而成年大鼠3组生存率无变化(P>0.05)。成年大鼠IPC-MI组短轴缩短率较单纯MI组明显升高,MI面积显著减小(P<0.05);与假手术组比较,IPC组6和12h心肌组织脂联素mRNA表达明显升高(P<0.05),血浆脂联素在0、6和12h显著升高(P<0.05)。老年大鼠IPC组各时间点心肌组织脂联素mRNA表达与假手术组无显著差异,血浆脂联素24 h明显升高(P<0.05)。结论成年大鼠IPC后心肌组织和血采脂联素表达均升高,心功能改善,老年大鼠脂联素变化不明显,提示脂联素参与成年大鼠IPC发挥的心肌保护作用。
Objective To investigate the effects of myocardial ischemic preconditioning (IPC) on cardiac function and the expression of adiponectin in myocardium and plasma of adult and aged rats. Methods Totally 85 adult and aged rats were randomly divided into IPC group (40 rats) and IPC (M1-M1) model. Only 30 adult and aged rats that did not block the flow of blood were perfused with 20 rats each randomly. The other 10 rabbits were given MI alone. Sham operation group and IPC group were observed at 0, 6, 12 and 24 h after IPC. Five adult and aged rats without coronary artery ligation were used as control group. Cardiac function was measured by M-mode ultrasound. Masson’s Trichrome staining was used to measure the area of MI. The expression of adiponectin and mRNA in myocardium was detected by immunohistochemistry and RT-PCR. The content of plasma adiponectin was detected by ELISA. Results The survival rate of the IPC-MI group was significantly lower than that of the MI group and the control group (P <0.05), while there was no difference between the three groups (P> 0.05). The short axis shortening rate of IPC-MI group was significantly higher than that of MI group and the area of MI was significantly decreased (P <0.05). Compared with sham operation group, the expression of adiponectin mRNA in IPC group was significantly increased at 6 and 12 h (P <0.05), plasma adiponectin increased significantly at 0, 6 and 12 h (P <0.05). Adiponectin mRNA expression was not significantly different between the IPC group and the sham operation group at each time point. Plasma adiponectin levels were significantly increased at 24 h (P <0.05). Conclusion The expressions of adiponectin and adiponectin in myocardial tissue and blood of adult rats are increased after IPC. The cardiac function is improved, while the changes of adiponectin in old rats are not obvious. It suggests that adiponectin participates in the myocardial protective effect of IPC in adult rats.