浅低温缺血预处理对未成熟心肌超微结构保护作用的影响

目的:研究IP复合32℃浅低温晶体停搏液保护状态对未成熟心肌缺血再灌注损伤细胞超微结构的影响。方法:应用Langendorff离体心脏模型,IP采用2次5min缺血、5min再灌注,实验分为IP+32℃浅低温组和单纯32℃浅低温组。心脏灌注St.ThomasⅡ停搏液,缺血30min,37℃再灌注30min。采用血流动力学、生物化学及立体定量方法分析IP的心肌保护效果及对心肌细胞超微结构的影响。结果:再灌注后30min,IP组的LVDP、+dp/dtmax、-dt/dtmax恢复率明显高于单纯32℃浅低温组(P<0.05)。再灌注末,IP组心肌ATP含量显著高于单纯32℃浅低温组(P<0.05)。IP组心肌MDA含量显著低于单纯32℃浅低温组(P<0.05)。IP组基本完好心肌细胞体积密度高于单纯32℃浅低温组(P<0.001),而严重损伤心肌细胞的体密度小于单纯32℃浅低温组(P<0.05),IP组心肌细胞间质体积密度小于单纯32℃浅低温组(P<0.05)。IP组心肌组织内皮细胞有显著变性的毛细血管断面计数显著高于单纯32℃浅低温组(P<0.05)。结论:IP复合32℃浅低温晶体停搏液对未成熟心肌缺血再灌注损伤细胞超微结构有较好的保护作用。

PROTECTIVE EFFECTS OF ISCHEMIC PRECONDITIONING WITH CRYSTALLOID CARDIAPLEGIA AND MILD HYPOTHERMIA ON ULTRASTRUCTURE OF IMMATURE MYOCARDIAL CELLS

Objective:To determine the protective effects of ischemic preconditioning (IP) on ultrastructure of myocardial cells of rabbit immature myocardium with mild hypothermia.Methods:Isolated neonatal rabbit hearts were subjected to two times of IP and then arrested by St.Thomas Ⅱcardioplegic solution . 30 minutes After ischemia at 32℃,30 minutes of reperfusion (37℃) was followed in Langendorff mode. Determinations of cardiac hemodynamics,biochemisty as well as stereological quantitation of myocardial ultrastructure after reperfusion were completed.Results:The results demonstrated that the recoveries of LVDP, +dp/dtmax、 -dp/dtmax in IPgroup were significantly higher than those of control(P<0.05)30 minutes after reperfusion,respectively. The ATP contents in IP group were significantly higher than control (P<0.05)whereas MAD were showed much lower in IPgroup when compared with its control (P<0.05) . Volume density(Vd) of myocardial cells which kept basic integrity in IP group was lager than that in control (P<0.001)and the Vd of severe destroyed myocardial cells in IP group was significantly less than the control (P<0.05). The statistics differences were detected with regard to the numbers of section of microvascular with destroyed endothelium in two groups (P<0.05) .Conclusions:Under the condition of crystalloid eardioplegia at 32℃, IP can remarkably achieve the better protective effect on myocardial ultrastructure of immature myocardium .