X线照射对大鼠心脏缺血再灌注损伤影响

Myocardial response to ischemia reperfusion injury in rats after X-ray irradiation

目的 观察大鼠心脏经X线照射后对缺血再灌注损伤的耐受性。方法 完全随机法将12只雄性大鼠分为对照组和照射组,照射组采用6 MV X线单次20 Gy经心前区照射构建RIHD模型。模型制备后第14天两组进行Langendorff离体心脏灌流并记录左室发展压、左室舒张末压、左室压力变化的最大速率和心脏冠脉流量,TTC染色法比较两组间缺血再灌注后心肌梗死面积。成组t检验差异。结果 全心缺血30 min再灌注60 min后照射组冠脉流量较对照组下降[（5.64 ± 0.35） ml/min比（8.38 ± 0.52） ml/min （P=0.002）],且照射组离体心功能恢复较对照组明显下降,包括左室发展压恢复值下降[（25.42±2.31） mm Hg（1 mm Hg=0.133 kPa）比（52.76±2.76） mm Hg（1 mm Hg=0.133 kPa） （P=0.000）]、左室压力上升或下降最大速率恢复值均降低[（547.04±78.74） mm Hg（1 mm Hg=0.133 kPa）/s比（1 100.05±83.35） mm Hg（1 mm Hg=0.133 kPa）/s （P=0.001）或（-408.81±56.74） mm Hg（1 mm Hg=0.133 kPa）/s比（-813.62±73.82） mm Hg（1 mm Hg=0.133 kPa）/s （P=0.002）]、左室舒张末压恢复值升高[（85.29±4.61） mm Hg（1 mm Hg=0.133 kPa）比（65.65±3.65） mm Hg（1 mm Hg=0.133 kPa） （P=0.012）]。X线照射引起大鼠心肌梗死面积百分比明显增加[（44.67±0.95）%比（30.46±0.96）%（P=0.000）]。结论 X线照射可引起大鼠冠脉损伤,降低心脏对缺血或再灌注损伤的耐受性,增加缺血或再灌注后心肌梗死面积。

Objective To observe myocardial tolerance to ischemia/reperfusion （I/R） injury in rats after exposure to X-ray irradiation. Methods Twelve male rats were randomly divided into control group and radiation group. The rat model of radiation-induced heart disease was established in the radiation group by precordial irradiation with 20.0 Gy of 6 MV X-ray in a single fraction. At 14 days after model establishment, the Langendorff perfusion technique was performed in the two groups and the cardiac parameters including left ventricular developing pressure （LVDP）, left ventricular end diastolic pressure （LVEDP）, maximal rate of left ventricular pressure rise/fall （＋/-LVdp/dtmax）, and coronary flow （CF） were recorded. Myocardial infarct size after I/R was compared between the two groups by 2,3,5-triphenyltetrazolium chloride staining. Results After 30 minutes of ischemia and 60 minutes of reperfusion, the irradiation group had a significantly slower CF than the control group （5.64±0.35 vs. 8.38±0.52 ml/min, P=0.002）. Moreover, the irradiation group had substantially poorer recovery of cardiac function in isolated hearts compared with the control group, as shown by a significantly reduced LVDP （25.4±2.31 vs. 52.76±2.76 mm Hg（1 mm Hg=0.133 kPa）, P=0.000）, significantly reduced＋/-LVdp/dtmax （547.04±78.74 vs. 1 100.05±83.35 mm Hg（1 mm Hg=0.133 kPa）/s,P=0.001;-408.81±56.74 vs-813.62±73.82 mm Hg（1 mm Hg=0.133 kPa）/s, P=0.002）, and a significantly increased LVEDP （85.29±4.61 vs. 65.65±3.65 mm Hg（1 mm Hg=0.133 kPa）, P=0.012）. X-ray irradiation induced a significantly increased percentage of myocardial infarct size in rats （44.67%±0.95% vs. 30.46%±0.96%,P=0.000）. Conclusions X-ray irradiation can induce coronary injury, reduce myocardial tolerance to I/R injury, and increase myocardial infarct size after I/R in rats.