药物延迟预处理减少在体幼兔缺血再灌注损伤后的心肌细胞凋亡

Delayed Preconditioning By Diazoxide Decrease Myocardial Apoptosis on an in vivo Rabbit Model

目的在完全模拟心脏体外循环手术的在体缺血再灌注损伤幼兔模型中，验证二氮嗪介导的延迟预处理是古能够减少心肌细胞凋亡。方法3～4周龄健康新西兰幼兔32只随机分为：对照组；缺血再灌注（I／R）组；二氮嗪（DZX）组：幼免24h前耳缘静脉注射DZX（1mg／kg）；DZX＋PDTC组：将实验用幼兔24h前耳缘静脉注射DZX（1mg/kg）及二硫代氨基甲酸吡咯烷PDTC（100mg／kg）。建立在体幼免体外循环缺血再灌注损伤模型，阻断升主动脉Ⅰh后开放循环再灌注6h，而对照组仅建立体外循环，不阻断升主动脉，经历实验组相同体外循环时间。取心室壁心肌做TUNEL染色检测凋亡细胞，Caspase-3酶活性的检测，Western Blot检测心肌细胞Bax和Bcl-2的表达，结果①TUNEL检测结果：缺血傅灌注损伤所导致的心肌细胞凋亡较对照组均显著增高（P〈0．01）；DZX组凋亡指数较I／P,组明显减少（P〈0．01）；加入PDTC后，凋亡指数又较DZX组明显增多（P〈001），②I／R组较DZX组Caspase3活性明显升高（P〈0．01）．但DZX组和DZX＋PDTC组Caspase3活性并无差别（P〉0．05）。③与I／R组相比DXZ组幼免心肌细胞Bcl-2／Bax显著增加（P〈0．01）；与DZX组相比DZX＋PDTC组幼免心肌细胞中Bcl-2／Bax显著减少（P〈0.05）。结论二氮嚷介导的延迟预处理能够减少心肌细胞凋亡；NFKB通过调控凋亡相关蛋白Bax、Bcl—2、Caspase-3的表达在未成熟心肌的延迟预处理中起着关键作用。

Objective To investigate wether the protective effect of delayed PC mediated by mito KATP opener Diazoxide could decrease myocardial apoptosis on an in-vivo rabbit model. Methods The 32 rabbits were randomized into control, I/R, DZX and DZX ＋ PDTC group. All the rabbits were established extracorporeal circulation （CPB）, and the rabbits in latter three groups experienced 1 hour aortic occlusion, and then were reopened the aorta and followed hy 6 hours reperfusion. The rabbits in control group received the same period of extracorporeal circulation without aortic occlusion. The rabbits in DZX group received DZX（1 mg/kg）intravenous injection 24 hours before CPB; the rabbits in DZX ＋ PDTC group received DZX （ 1 mg/kg） and PDTC（ 100 mg/kg） intravenous injection before CPB. The ventricular myocardium was harvested for TUNEL arid West ern Blot test. Results Compared with controls, the rabbits in other three groups showed significant higher apoptosis index, as well as higher activity of Caspase 3. The rabbits in DZX group had significant lower apoptosis index than that of I/R group to DZX ＋ PDTC group. And the ratio of Bci -2 to Bax in DZX group was also found significant higher than I/R group and DZX ＋ PDTC group. Conclusion Delayed PC elicited by mito KATP opener DZX could decrease post ischemic-reperfusion myocardial apoptosis. The activation of transcription factor NF-kB might play an essential role in the delayed PC.