脂肪乳后处理对心脏缺血再灌注损伤的保护作用

目的 研究脂肪乳预处理和后处理是否具有心脏保护作用,并初步探讨其机理.方法 雄性SD大鼠20只.采用Langendorff 灌流模型,随机分为4组:持续灌注组(CTL组,持续灌注3 h 50 min),缺血再灌注组(ISCH 组,心脏平衡50 min, 37℃缺血45 min, 复灌3 h),脂肪乳预处理(I-preC组,脏平衡30 min, 给予含30%脂肪乳的灌注液预处理15 min,洗脱15 min, 37 ℃缺血45 min, 复灌3 h),和脂肪乳后处理组(I-postC组,心脏平衡50 min,37 ℃缺血45 min,复灌3 h,复灌开始给予含30%脂肪乳的灌注液15 min).基础和复灌期间连续监测心率(HR)和机械功能(LVDP).平衡20 min和复灌60min时测定流出液中LDH的含量.复灌结束, 剪下心脏左室前壁,做病理切片.余下的心肌组织液氮速冻后-70 ℃冰箱保存,做Western Blotting.结果 与ISCH组相比,I-postC组心脏做功增强,而I-preC并不增加左室做功.与ISCH 组相比,I-preC组和I-postC组复灌60 min时LDH的释放均降低,I-postC组心肌凋亡细胞指数降低(P＜0.05);I-preC组和ISCH组心肌凋亡细胞指数之间差异无统计学意义.与ISCH组相比,I-postC组的Bax表达量较低;I-postC组的Bcl-2的表达量较高.与ISCH组相比,I-preC组Bax的表达量比较高,I-postC组Bcl-2的表达量较低.结论 脂肪乳后处理通过抑制心肌细胞凋亡而增强心脏机械做功,并减少LDH 的释放而减轻心肌缺血再灌注损伤.

Apoptosis Mechanism of Intralipid Postconditioning to Reduce Ischemia Reperfusion Injury of Islated Rat Hearts

OBJECTIVE: To test the effect of intralipid, a solution containing soybean oil, egg phospholipid and glycerol, on protecting perfused rat hearts against ischemia/reperfusion injury (IR) and to explore possible cardiomyocyte apoptosis mechanism involved. METHODS: Twenty Sprague-Dawley rtas were perfused with Kreb-Henseleit buffer on Langendorff apparatus. The rats were randomly allocated to 4 groups. The control group of rats were perfused for 3 hours and 50 minutes without cardiplegia ischemia. The hearts of the other three groups of rats (I-preC, I-postC, and ISCH) were subjected to 45 minutes of ischemia and 3 hours of reperfusion. The I-preC group was pre-treated with 15 minutes of intralipid followed by 15 minutes of wash out. The I-postC group was treated by 15 minutes of intralipid at the onset of reperfusion. The ISCH group served as untreated ischemic control. The LVDP (Left Ventricular Developed Pressure) and HR were measured before and after reperfusion. The LVW was calculated as LVDP x HR. LDH were measured 20 minutes after perfusion and 60 minutes after reperfusion. TUNEL staining was used for identification of apoptotic cells. After 3 hours of reperfusion, the changes of expressions of Bcl-2 and Bax were examined by Western Blotting. RESULTS: Slightly mechanic function attenuation and low LDH release were found in the control group, along with little apoptosis. By contrast, significantly decreased mechanical function and more cardiocyte apoptosis were found in the ISCH group. Intralipid postconditioning improved LVW and reduced LDH activity significantly. The improvement was accompanied by increased protein expression of Bcl-2 and decreased Bax protein level. Intralipid preconditioning decreased LDH level only. No significant differences in protein level of Bcl-2 and Bax were found between the I-preC and ISCH group. CONCLUSION: Intralipid postconditioning improves cardiac mechanical performance through inhibiting cardiocyte apoptosis and reducing LDH activity. Intralipid preconditioning reduces LDH level but does not inhibit cardiocyte apoptosis.