缺血预适应对老年大鼠缺血-再灌注心肌的影响

The Effect of Ischemic Preconditioning on Myocardial Ischemic Reperfusion of Elderly Rats

目的探讨缺血预适应（ischemic preconditioning,IPC）对老年大鼠缺血-再灌注损伤（I/R）后心肌的影响。方法取Wistar大鼠56只,其中21~23月龄（老年鼠）和4~5月龄（青年鼠）各28只,建立离体心脏Langendorff灌注模型,按随机数字表法分为7组（每组8只）：青年对照组、青年I/R组、青年IPC组、老年对照组、老年I/R组、老年IPC组、老年强化IPC组。对照组采用全心灌流90 min,不做任何处理;I/R组采用心脏平衡灌流30min后,缺血30 min。

Objective To investigate the effect of ischemic preconditioning （IPC） on myocardial ischemic reperfusion injury（I/R） of elderly rats. Methods Fifty-six Wistar rats, of which there were 28 aged from 21- 23months（elderly rat） and 28 aged from 4-Smonths （young rat）, were used to build isolated heart perfusion Langendorff model. The rats were divided into 7 groups with random number table（8 in each group）： adult control group, adult I/R group, adult IPC group, elderly control group, elderly I/R group, elderly IPC group and elderly enhanced IPC group. The control group underwent a 90 rain perfusion without any intervention; the I/R group underwent a 30-min equilibration period, then a 30-min ischemia and a 30-min reperfusion; the IPC group underwent a 10-min equilibration period, then a 5-min ischemia for twice and a 5-min reperfusion, after that a 30-min ischemia and a 30-min reperfusion; the enhanced IPC group underwent a 10-min equilibration period, then a 5-min ischemia for 4times and a 5 min reperfusion, after that a 30 min ischemia and a 30-min reperfusion. The recovery rates of cardiac output（CO）, left ventricular developed pressure （LVDP）, the maximum rising and descending rate of left ventricular pressure （±dp/dtmax） after a 30-min reperfusion were compared among groups. The activity of creatine kinase （CK） in coronary outflow, the level of malonyldialdehyde （MDA） and superoxide dismutase （SOD） before ischemia and after a 30 min reperfusion were detected. The myocardial infarction areas were compared among groups. Results After a 30-min reperfusion, compared with adult I/R group, in adult IPC group CK reduced significantly（89. 48 ±18.72 U/L vs. 115.76±16.72 U/L, q= 6. 061, P〈0. 01）, the level of MDA decreased significantly（9.53 ±3.44 nmol/ml vs. 16.84±2. 29 nmol/ml, q = 7. 732, P〈 0. 01 ）, the level of SOD increased significantly （584. 7 ±122. 62 U/ml vs. 429.46±85.24 U/ml,q = 4. 754, P〈0. 01 ）, the recovery rates of CO, LVDP, 4- dp/dtmox and -- dp/dtmax increased significantly（78.69%±9. 68% vs. 65. 10%/002_8. 63%,83. 61%±8.46% vs. 67. 232±8. 68%,81. 684±8. 68% vs. 67.89±6.89%,89. 79±7. 78% vs. 66. 79±8. 46G,P〈0. 01）, the myocardial infarction areas reduced significantly （5.25% ±4. 33% vs. 14. 75 %± 8. 02 %, q =7. 458, P〈 0. 01） .There was no statistical significance between elderly IPC group and elderly I/R group in the above indexes（P〉0. 05）. However, There was statistical significances between elderly enhanced IPC group and I/R group. CK reduced significantly （88. 60± 28.32 U/L vs. 105.76±9.64 U/L,q=5. 620,P〈0.01） ,the level of MDA decreased significantly（8.38±3.36 nmol/ml vs. 16.80± 3.06 nmol/ml,q=7. 500,P〈0. 01） ,the level of SOD increased significantly（558. 87±78. 66 U/mlvs. 433.75±86.65 U/mi,q= 7. 335, P〈0. 01 ）, the recovery rates of CO, LVDP, q-dp/dtmax and --dp/dtmax increased significantly （77.99%±10.02% vs. 66.26%±9.78%,85.59%±6.67% vs. 73.90%4-6.66%,83.87%±9.98% vs. 68.90%± 8.68% ,86.01%± 7.66% vs. 70. 39%±7. 98%, P〈0.01）, the myocardial infarction areas reduced significantly （7.95±6.32% vs. 15.68%±10.36%,q=8.680, P〈0.01） elderly rat hearts has weakened. The enhanced IPC is able to regain Conclusion The protective effect of IPC on I/R the protective effect of IPC on elderly rat hearts.