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目的 :探讨反复短暂缺血剌激导致缺血预适应 (IP)对心肌毛细血管床功能的影响。方法 :复制套扎前降支冠状动脉犬模型。IP组给予缺血 5min ,灌注 5min ,反复 4次 ;假手术组不予缺血与灌注剌激 ,观察 4 0min。分别于实验前、第 1次缺血与再灌注及第 4次缺血与再灌注末行心肌声学造影 ,最后对心肌毛细血管进行超微结构观察 ,并定量分析 ,做组内及组间比较。结果 :第 4次缺血较第 1次缺血其声学显影最小缺损面积百分比 (ADmin % )由32 6 %± 5 7%降至 2 1 8%± 5 2 % (P <0 0 5 ) ,定量分析指标峰值 (PI)、曲线下面积 (AUC)、峰减半时间 (HT)均增高 ;心肌毛细血管数、管腔内径、内皮细胞厚度及内皮细胞超微结构均无明显差别。结论 :反复短暂缺血增加心肌微循环血液灌注但无毛细血管超微结构改变 ,提示IP促发心肌毛细血管床功能性开放
Objective: To investigate the effect of repeated transient ischemic stimulation on myocardial capillary bed function induced by ischemic preconditioning (IP). Methods: The anterior descending coronary artery canine model was reproduced. IP group was given ischemia for 5min, perfusion 5min, repeated 4 times; sham-operated group without ischemia and perfusion stimuli observed 40min. Before the experiment, the first ischemia and reperfusion, and the fourth ischemia and reperfusion at the end of myocardial contrast echocardiography, the last of the myocardial capillary ultrastructure observation, and quantitative analysis, intra-group and between groups . Results: The minimum ischemic area percentage (ADmin%) of the fourth ischemia was lower than that of the first ischemia from 32 6% ± 5 7% to 21 18% ± 52% (P 0 05) Quantitative analysis showed that the peak value (PI), area under the curve (AUC) and peak half-time (HT) increased. There was no significant difference in the number of capillary capillaries, lumen diameter, endothelial cell thickness and ultrastructure of endothelial cells. CONCLUSION: Repeated transient ischemia increases myocardial microcirculation blood perfusion but no capillary ultrastructure changes, suggesting that IP promotes the functional opening of myocardial capillary bed