左旋卡尼汀预处理对离体兔心缺血再灌注致心肌损伤及MDA、SOD的影响

1、左旋卡尼汀预处理对离体兔心缺血/再灌注致心肌损伤及MDA、SOD的影响         10-10-30 09:49:00     编辑：studa20                       作者：赵宁军，许铁，叶英，燕宪亮，梁高永，刘蓓 【摘

2、要】  目的 观察左旋卡尼汀（L-CN）预处理对离体兔心缺血/再灌注致心肌损伤及丙二醛（MDA）、超氧化物歧化酶（SOD）的影响。方法 采用离体兔心Langendorff灌注实验模型,离体兔心12只随机分成缺血/再灌注组（I/R组）和L-CN预处理组，每组6只。I/R组灌注K-H液25 min，（兔心）4标准St.Thomas停搏液(K+ 16 mmol/L)至心脏停搏,45 min后恢复K-H液灌注20 min; L-CN预处理组灌注K-H液10 min，再予L-CN续灌15 min，余步骤同I/R组。测定再灌注末心肌组织中MDA、SOD的活性； 2，3，5-三苯基氯化四氮唑（TT

3、C）染色测定心肌存活面积百分比。结果 L-CN预处理组SOD活性明显高于I/R组（P0.01），MDA含量明显低于I/R组（P0.05）。L-CN预处理组心肌存活面积百分比高于I/R组(P0.05）。结论 L-CN预处理对高钾停搏离体兔缺血/再灌注心脏具有抑制氧化应激、提高抗氧化能力的作用，可减轻心肌损伤。 【关键词】  缺血/再灌注损伤;离体心脏;左旋卡尼汀;预处理;家兔Abstract: Objective  To investigate the effects of L-carnitine (L-CN) preconditioning on levels of sup

4、eroxide dismutase (SOD) and malondialdehyde (MDA) against ischemia/reperfusion-induced myocardial injury in isolated rabbit hearts. Methods  The experiment was performed on isolated rabbit hearts perfused on Langendorff apparatus. 12 rabbit hearts were randomized into ischemia/reperfusion group

5、 (I/R group) and L-CN preconditioning group (n=6 each). The I/R group was firstly perfused with Krebs-Henseleit buffer (K-H) solution at 4 for 25 min, followed by St. Thomas solutions (K+ 16 mmol/L) until cardiac arrest for 45 min and then reperfused with K-H solution for 20 min. The treatment of L-

6、CN preconditioning group was similar to that of the I/R group, except that this group was initially perfused with K-H solution for 10 min and then perfused with L-CN. At the end of reperfusion, the contents of MDA, the activity of SOD were measured. The percentage of survival areas of myocardium was

7、 measured by using 2,3,5-triphenyltetrazolium chloride (TTC) stain. Results  In contrast to the findings in the I/R group, the percentages of surviving myocardium areas in the L-CN preconditioning group were higher (P<0.05). SOD content in L-CN preconditioning group was significant higher th

8、an that in I/R group (P<0.01). MDA content in L-CN preconditioning group was significantly lower than that in I/R group (P<0.05). Conclusion  L-CN preconditioning can attenuate the myocardium injury by inhibiting oxidative stress and increasing the anti-oxidative capacity to the isolated

9、rabbit heart undergoing cardiac ischemia due to high potassium-induced cardiac arrest and reperfusion.    Key words:  ischemia/reperfusion-induced injury; isolated heart;  L-carnitine; preconditioning; rabbit    成熟心肌的主要能量来源是脂肪酸,约占总能量来源的60%80%,且主要是依靠外源性脂肪酸来提供能量

10、。左旋卡尼汀（L-carnitine, L-CN）是人体脂肪酸代谢的必需辅助因子，可以改善心肌缺血时的异常代谢状况，加速脂肪的-氧化，并增加葡萄糖的氧化利用1。本实验应用离体兔心Langendorff灌注模型观察L-CN预处理对高钾停搏离体兔心缺血/再灌注损伤的影响，并探讨其可能的作用机制。1  材料和方法1.1  材料 采用健康家兔（由徐州医学院实验动物中心提供）12只，雌雄不拘，体重2.22.5 kg,平均(2.3±0.2) kg。L-CN为美国Sigma公司产品，2,3,5三苯基氯化四氮唑（2,3,5-triphenyltetrazolium ch

11、loride, TTC）购自上海国药医药集团公司，SOD、MDA测定试剂盒购自南京建成生物工程研究所。其余试剂均为国产分析纯。1.2  实验方法兔耳缘静脉注射肝素300 U/kg，5 min后击头部致昏,迅速开胸取心连接于改良Langendorff灌注装置上，以95% O2和5% CO2饱和Krebs-Henseleit溶液(K-H液)逆行灌注，温度37，灌注压力为750 mmHg (1 mmHg=0.133 kPa)。K-H液成分(mmol/L)：NaCl 118、 KCl 4.7、NaH2PO4 1.19、MgCl2 1.19、CaCl2 2.5、NaHCO3 24.8、葡萄糖1.1、EDTA-2Na 0.125，pH 7.4。采用离体兔心Langendorff灌注实验模型,根据预处理药物浓度不同（参见Loster等2文献），随机分成缺血/再灌注组（I/R组）、左旋卡尼汀预处理组（L-CN预处理组），每组6只。离体心脏以95%O2和5%CO2混合气体饱和的K-H液平衡灌注10 min后，I/R组继续灌注K-H液15 min。L-CN预处理组在平衡灌注后予浓