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

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

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-αmRNA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-αmRNA及其蛋白水平的变化:脑死亡组PKC-αmRNA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。

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.