二氮嗪后处理对缺氧复氧成年大鼠心肌细胞保护作用的体外研究

目的研究线粒体ATP-敏感性钾通道（mitoKTP）开放剂二氮嗪（diazoxide，DZ）后处理对缺氧复氧成年大鼠心肌细胞的影响。方法体外培养原代成年大鼠心肌细胞建立缺氧复氧损伤模型，随机分为5组：Normal组（在CO2培养箱中持续培养6h）；H／R组（缺氧3h复氧3h）；DZ组（缺氧3h复氧3h，在复氧5min时给予100mol／LDZ）；DZ＋5-羟葵酸盐（5-hydmxydecanoate，5-HD）组（缺氧3h复氧3h，在缺氧末给予100mol／L选择性mitoK。通道阻断剂5-HD，然后在复氧5min时给予100mol／LDZ）；5-HD组（缺氧3h复氧3h，在缺氧末给予100mol／L5-HD）。复氧3h末检测各组培养基中乳酸脱氢酶（LDH）漏出量和丙二醛（MDA）含量，TUNEL法测定心肌细胞凋亡指数、测定心肌细胞收缩幅度。结果与Normal组相比，其他4组培养基中LDH漏出量和MDA含量明显升高，心肌细胞凋亡指数也显著增高，心肌细胞收缩幅度降低（P〈0．05）；与H／R组比较，DZ后处理使培养基中LDH漏出量及MDA含量减少、心肌细胞凋亡指数降低，复氧后心肌细胞收缩幅度明显增高（P〈0．05），但是缺氧末即刻给予5-HD可以逆转DZ的作用（P〈0．05）；5-HD组与H／R组相比各指标差异无统计学意义（P〉0．05）。结论Dz后处理可以通过开放mitoK。通道对缺氧复氧成年大鼠心肌细胞发挥保护作用。

The cardioprotective effects of diazoxide postconditioning against hypoxia/reoxygenation injury in cultured adult rat cardiac myocytes

Objective To investigate whether mitochondrial ATP - sensitive potassium channel （ mitoKATP channel） opener diazoxide （DZ） postconditioning during early reoxygenation confers cardioprotection against hypoxia/reoxy- genation injury in cultured adult rat cardiac myocytes. Methods The model of isolated adult rat cardiac myocytes was established and randomly divided into 5 groups： normal group （ caridocytes were incubated at 37~C in a humidified atmos- phere of 5% CO2 and 95% air for 6 hours） ; H/R group （cardiocytes were exposed to 3 hours of hypoxia followed by 3 hours of reoxygenation） ; DZ group （ cardiocytes were exposed to 3 hours of hypoxia followed by 3 hours of reoxygenation , 100 mol/L DZ was added in medium at the site of 5 min after reoxygenation） ; DZ ＋5 -hydroxydecanoate （5 -HD） group （ cardiocytes were exposed to 3 hours of hypoxia followed by 3 hours of reoxygenation , 100 mol/L selective mi- toKATP channel blocker 5 - HD was added in medium rightly after hypoxia and 100 mol/L DZ was added in medium at the site of 5 min after reoxygenation） ; 5 - HD group （ 3 hours of hypoxia followed by 3 hours of reoxygenation , while 100 mol/L 5 - HD was added in medium after hypoxia） . After treatment lactate dehydrogenase （LDH） release and ma- londialdehyd （MDA） level in culture medium were determined with assay kits; the apoptotic index was evaluated with TUNEL; the cardiomyocytes contraction was measured. Results Compared with the normal group,the LDH release, the level of MDA and the apoptotic index were greatly increased in the other 4 groups, while the contracile function were de- creased （P 〈0.05）. Compared with the H/R group,the LDH release, the level of MDA and the apoptotic index in di- azoxide group were significantly decreased,while the contracile function were greatly improved （P 〈0.05 ） ; these effects were blocked with administration of 5 - HD right after hypoxia （P 〈 0.05 ）. There was no statistical difference between H/R group and 5 - HD group （P 〉 0.05）. Conclusion These data indicate that diazoxide has protective effect on adult rat cardiac myocytes subjected to hypoxia/reoxygenation via opening of mitoKATP channel.