脑死亡对巴马小型猪心脏结构与功能的影响及其机制的实验研究

目的： 探讨脑死亡状态对巴马小型猪心脏结构与功能的影响及蛋白激酶C (PKC)在其发生机制中的作用。方法: 巴马小型猪10只，随机分为脑死亡组与对照组，每组5只。应用改进的缓慢间断颅内加压法建立脑死亡模型，对照组仅开颅麻醉维持。于脑死亡后6、12和24 h检测血清中肌钙蛋白Ｔ(cTnT)、IL-1β、IL-6及TNF-α水平，24 h开胸取心肌组织，HE染色观察心脏组织结构变化，电镜观察心脏超微结构变化，免疫组化染色观察PKC-α蛋白表达，RT-PCR法检测PKC-α mRNA表达。结果: （1）心肌组织学变化：脑死亡后24 h可见心肌结构改变，光镜下见心内膜下片状出血，心肌溶解，断裂；电镜下见线粒体水肿，肌纤维模糊融合，嵴部分消失，膜部分融合。（2）血清cTnT变化：脑死亡组血清cTnT自脑死亡后6 h开始升高，并随时间延长而逐渐升高；各时点两组相比脑死亡组明显高于对照组（P<0.05）。（3）炎症介质变化：脑死亡组IL-1β、IL-6、TNF-α水平自6 h开始升高，并随时间延长而逐渐升高；各时点两组相比脑死亡组明显高于对照组（P<0.05）。（4）心肌细胞中PKC-α mRNA及其蛋白水平的变化：脑死亡组PKC-α mRNA及其蛋白表达水平均明显高于对照组（P<0.05）。结论: 脑死亡导致巴马小型猪心脏结构与功能的损伤，炎症介质水平升高；脑死亡时心脏PKC-α 表达水平升高。PKC-α的活化可能参与了脑死亡状态下心脏的损伤过程。

Experimental study on how brain-dead state affects the heart structure and function of Ba-Ma mini pigs and the mechanism

AIM:To investigate how brain-dead state affects the heart structure and function and the effect of PKC-α in BA-Ma mini pigs.METHODS:Ten Ba-Ma mini pigs were randomized into 2 groups: brain-dead group (n=5),and control group (n=5). The brain-dead model was made by increasing intracranial pressure,while the control group was maintained anesthesia for 24 h. The concentrations of cTnT,TNF-α,IL-1β and IL-6 in serum were determined at 6,12 and 24 h after brain death. At 24 h,heart tissues were observed by HE staining and electron microscope. The expression of PKC-α was detected by immunohistochemistry and RT-PCR.RESULTS:(1) Histological changes of myocardium: flaky bleeding under endocardium and dissolution of myocardium were found in optical microscope. In electron microscope dropsical mitochondria and confluent muscle fiber were found. (2) Changes of serum cTnT: serum cTnT for brain-dead group began to increase gradually since 6 h,and were significantly higher at each time point than those in control group (P<0.05). (3) Changes of inflammatory factors: IL-1β,IL-6,and TNF-α in brain-dead group began to increase gradually since 6 h,and were significantly higher at each time point than those in control group (P<0.05). (4) Changes of PKC-α expression: PKC-α mRNA and protein expressions in brain-dead group increased significantly at 24 h (P<0.05).CONCLUSION:Brain death may evoke heart structure and functional injury,and increase the levels of inflammatory factors and PKC-α. The activation of PKC-α may participate in the process of heart injury.