缺血预处理减轻在体家兔心肌细胞凋亡

对麻醉家兔心肌缺血－再灌注（ｉｓｃｈｅｍｉａ－ｒｅｐｅｒｆｕｓｉｏｎ,ＩＲ）模型上,观察ＩＲ和缺血预处理（ｉｓｃｈｅｍｉｃ ｐｒｅｃｏｎｄｉｔｉｏｎｉｇｎ,ＩＰ）对血流动力学、心外膜电图、心肌梗塞范围、心肌细胞调亡和调亡相关调控基因蛋白（Ｆａｓ、Ｂｃｌ－２、Ｂａｘ等）的影响。所得结果如下：⑴在ＩＲ过程中,动脉血压、心率和心肌耗氧量进行性降低;心外膜电图ＳＴ段在缺血期明显抬高（Ｐ＜０．００１）,再灌

Ischemic preconditioning reduces cardiomyocytic apoptosis in rabbit heart in vivo

The effects of ischemia-reperfusion (IR) and ischemic preconditioning (IP) on hemodynamics, epicardial electrography, myocardial infarct size, cardiomyocytic apoptosis and gene proteins involving apoptosis (Fas, Bcl-2 and Bax) were observed in aneasthetized rabbit myocardium. The results are as follows. (1) During ischemia-reperfusion, heart rate, arterial blood pressure and myocardial oxygen consumption were reduced progressively. The epicardial electrographic ST-segment was elevated significantly during ischemia (P<0.001)and recovered to the baseline during reperfusion. (2) The infarct size occupied 57.7+/-2.0% of the ischemic myocardium in IR group while IP reduced the infarct size to 27.7+/-1.5% (P<0.01). (3) DNA ladder pattern of ischemic myocardium was revealed by agrose gel electrophoresis in IR group while it was not found in IP group. Apoptotic cardiomyocytes were sparse within the ischemic myocardium at risk in IP as compared with those in IR heart. Apoptosis rate of the ischemic myocardium from IR and IP groups detected by flow cytometry was 11.2+/-0.4% and 6.35+/-0.2% (P<0.01), respectively. (4) Fas and Bax protein expression in the ischemic myocardium of IR and IP groups was elevated as compared with those in non-ischemic myocardium group (P<0.05). The Fas protein expression of IR group was higher than that of IP group (P<0.05). Bcl-2/Bax ratio of IR group was lower than that in non-ischemic myocardium (P<0.01). From the results, it is suggested that IP decreases cardiomyocytic apoptosis induced by IR and this action is mediated by the reduction of Fas protein expression.