鸟氨酸脱羧酶/多胺系统在大鼠缺血预适应心肌保护中的作用

目的：探讨鸟氨酸脱羧酶（ODC）/多胺系统在缺血预适应（IPC）心肌保护中的作用。方法:应用离体灌流大鼠心脏复制模拟心肌缺血/再灌注模型。心脏随机分为6组：对照组 (control)、缺血/再灌注组 (IR)、弱缺血预适应组 (IPCw)、强缺血预适应组 (IPCs)、IPCw+多胺抑制剂组 (DF-EG-IPCw)和IPCs+多胺抑制剂组(DF-EG-IPCs)。免疫印迹法定量分析多胺合成限速酶鸟氨酸脱羧酶 (ODC)的表达；高效液相色谱测定心肌组织中的多胺（腐胺、精脒、精胺）含量；Powerlab多导生理记录系统记录心脏功能；氯化三苯基四氮唑 (TTC) 染色检测心肌梗死面积；TUNEL方法检测细胞凋亡率，比较其中的差异性。结果:（1）与对照组比，IR组ODC表达下调，腐胺含量增加，精胺含量减少，总多胺池减少（P<0.05），此时心功能下降（LVDP、HR、CF均低于对照组，P<0.05），心肌梗死面积及心肌细胞凋亡率增加（P<0.05）；（2）与IR组比，弱及强缺血预处理组（IPCw、IPCs）心肌ODC表达上调，腐胺含量减少，精胺含量增加，总多胺池增加（P<0.05或P<0.01），此时大鼠心功能有明显改善（LVDP、HR、CF与IR组比，P<0.05），心肌梗死面积及心肌细胞凋亡率均明显降低（P<0.01）；（3）给予多胺抑制剂后，心肌ODC表达，腐胺、精脒、精胺及总多胺池含量均明显降低（DF-EG-IPCw组 vs IPCw组；DF-EG-IPCs组vs IPCs组，P<0.05或P<0.01），心功能明显下降（P<0.05），心肌梗死面积及细胞凋亡率均明显增加（P<0.05）。结论:缺血预适应能明显上调大鼠心肌ODC/多胺系统，减轻缺血/再灌注心肌损伤；多胺合成代谢抑制剂取消了预适应介导的心功能改善、缩小心肌梗死面积及减少心肌细胞凋亡的作用，提示ODC/多胺系统可能参与了缺血预适应介导的心肌保护作用。

Protective role of ornithine decarboxylase (ODC)/polyamines system in the myocardium induced by ischemic preconditioning in rats

AIM: To explore the protective role of ornithine decarboxylase (ODC)/polyamines system in the myocardium induced by ischemic preconditioning in rats. METHODS: The experiment model of simulating myocardial ischemia-reperfusion was replicated by Langendorff perfused rat heart. The hearts were randomly divided into six groups: control group, ischemic-reperfusion group (IR), weak ischemic preconditioning group (IPCw), strong ischemic preconditioning groups (IPCs) and inhibitor groups (DF-EG-IPCw and DF-EG-IPCs). The expression of ODC was quantified by Western blotting analysis. The contents of polyamines (putrescine, spermidine, spermine) in cardiac tissue were detected with high performance liquid chromatography. The hemodynamics was obtained using the PowerLab 8/SP TM data acquisition system. The infarct size was measured using triphenyltetrazolium chloride (TTC) staining and the apoptosis cardiomyocytes were observed under optic microscope after TUNEL method treatment. RESULTS: In contrast with control group, in IR group the putrescine contents increased, the expression of ODC was down-regulated, the contents of spermine and the total polyamine pool decreased (P<0.05). At the same time, the cardiac function declined, with an increase in myocardium infarct size and the apoptosis rate of cardiomyocytes (P<0.05). When compared with IR group in terms of LVDP, HR and CF, both IPCw and IPCs groups had significant improvements in cardiac functions (P<0.05). These two groups also had smaller myocardium infarct size (P<0.01) and apoptosis rate of cardiomyocytes (P<0.01). When compared with IR group, the expression of ODC, the contents of spermine and the total polyamine pool increased in both IPCw (P<0.05) and IPCs groups (P<0.01), but the putrescine contents declined. In the respective inhibitor groups of the weak and ischemic preconditioning, the expression of ODC and the levels of putrescine, spermidine, spermine and the total polyamine pool decreased remarkably (DF-EG-IPCw vs IPCw, P<0.05; DF-EG-IPCs vs IPCs, P<0.01), while the myocardium infarct size and apoptosis rate of cardiomyocyte were relatively bigger in both inhibitor groups (P<0.05). Also, the heart function decreased significantly in terms of LVDP, HR and CF compared to their matched ischemic preconditioning group (P<0.05). CONCLUSION: Ischemic preconditioning significantly up-regulates the ODC / polyamines system in Langendorff perfused rat hearts and provides protective effects on myocardium with ischemia/reperfusion injury. Inhibition of bio-synthesis of polyamine abolishes the cardiac function improvement and the decreases the infarct size and apoptosis rate induced by ischemic preconditioning. It reveals that the ornithine decarboxylase (ODC) /polyamines system may be involved in the protection of myocardium induced by IPC in rats.