左旋卡尼汀对大鼠心脏缺血-再灌注损伤能量代谢的影响

目的：观察左旋卡尼汀对离体大鼠心脏缺血-再灌注损伤的作用及对心肌细胞能量代谢的影响。方法：将制备成功的Langendorff离体心脏模型随机分成3组（各8只）。正常对照组（CON组）：K—H液灌注65min；左旋卡尼汀组（L—CAR组）：离体心脏用K—H液平衡15min后，K—H液中加入5mmol／L左旋卡尼汀继续灌注20min．然后全心停灌20min，再用相同的液体复灌30min；心肌缺血-再灌注组（MIRI组）：整个实验过程同L—CAR组．但灌注液中不含左旋卡尼汀。比色法测定冠脉流出液中乳酸脱氢酶（LDH）含量，高效液相色谱法测定再灌注末心肌组织中腺苷酸的含量。结果：缺血前各组LDH活性差异无统计学意义（P〉0．05），再灌注末L—CAR组LDH含量明显低于MIRI组（P〈0．01），而心肌组织ATP、ADP、总腺苷酸水平及能荷则高于该组（P〈0．05，P〈0．01）。结论：左旋卡尼汀对缺血-再灌注心肌有保护作用，其保护机制与改善心肌能量代谢有关。

Effects of L-carnitine on Energy Metabolism of Myocardial Ischemia-Reperfusion Injury in Rats

Objective: To study the effects of L-carnitine on myocardial ischemia-reperfusion injury and energy metabolism in rats. Methods: Twenty-four Langendorff isolated heart models were randomly divided into three groups (n= 8 in each group) including control group (CON group) in which hearts were perfused for 65 min with oxygenized Krebs-Hensleit (K-H) buffer solution, L-CAR group in which hearts were first perfused for 15 min with K-H solution, then 5 mmol/L L-carnitine was added into K-H solution, after 20 min, kepf no for 20 min perfusion and bast hearts were reperfused with the same solution for 30 min, myocardial ischemia-reperfusion (MIRI) group in which the whole experimental procedures were the same as the L-CAR group, but the K-H solution did not contain L-carnitine. Lactate dehydrogenase (LDH) in the coronary effluent was measured by colorimetry and adenine nucleotide in myocardial tissue was determined by chromatogram. Results: There were no significant differences among three groups of LDH before ischemia (P < 0.05). LDH activity significantly decreased in L-carnitine group compared with MIRI group after reperfusion (P < 0.01), and ATP, ADP, TAN and EC levels of myocardial tissue increased in L-carnitine group compared with MIRI group (P < 0.01, P < 0.05). Conclusion: L-carnitine has protective effects on myocardial ischemia-reperfusion injury, the mechanism of the protection may be related to the improvement of energy metabolism.