亚低温对心肌缺血的影响

目的观察亚低温对垂体后叶素所致实验性大鼠心肌缺血的影响,并探讨其发生机制。方法实验动物随机分成5组,每组10只,A组为常温缺血组;B组为常温硝酸甘油治疗组;C组为低温缺血组;D组为低温硝酸甘油治疗组;E组为对照组。结果A组心电图的阳性率最高,B组其次,E组最低,C组次低,D组介于B组与C组之间。低温C组的左心室功能较常温A组增加。比较A组、C组、E组的病理切片,E组正常,A组的阳性切片主要表现为心肌细胞疏松化,肌纤维呈颗粒状(早期缺血改变),C组以心外膜血管扩张充血,心肌细胞间水肿,局灶性心肌细胞疏松化为主。结论亚低温能减轻垂体后叶素所致的心肌损伤,改善左心室功能,对硝酸甘油的扩张冠状血管作用无明显影响。

Effect of mild hypothermia on myocardial ischemia

ObjectivesTo observe the effect of mild hypothermia on myocardial ischemia caused by Pituitrin,investigate theunderlying mechanism.Methods50 Wistar rats were randomized to five groups : bolus group E,myocardial ischemiagroup A with normothermia,myocardial ischemia group C with hypothermia,myocardial ischemia group Btrea-ted withnitroglycerin under normal temperature,and myocardial ischemia group Dtreated with nitroglycerin under lowtempera-ture,each group has 10 rats.The A,C,Egroups were treated withsaline 1ml bellyinjecting;group B,Dtrea-ted withnitroglycerin(5mg/kg).30 minutes later pit(30U/kg) was given to each group except for the group E.Record theECG,and LVSP±dp/dtmax of group Aand C.Core temperature was measured withthermistor.The mild hypothermiagroup received cooling under the body with the 4 ℃saline bag.The core temperature was dropped to 32-35℃,whilethe control group’s body temperature was kept above 37℃.afterwards,hearts were excised and cut to se-veral sectionsstained with HEfor observing the degree of myocardial ischemia.Results1.Comparison of the electrocardiogramnegativerate.The negative rate of hypothermia group C was the most high for 80 % which was compared with A,B,D groups.The negative rate of group Dtreated wfith nitroglycerin under lowtemperature was the second.Group Btreated with ni-troglycerin under normal temperature was higher than group A without nitroglycerin.The difference was significant be-tween group Aand C(P<0.01).There was difference as comparing group Band D with group A(P<0.05).There wasno difference between Band D,Cand Dgroup.2.Heart function measurement after the treatment with pit,both of themdeduced.Difference was significant betweenthe two groups.The-dp/dtmaxand LVSP had the same result.3.HE Nor-mothermia group A:cardiac myocyte became rarefaction,muscle fiber reported the grain form(earlier period of ischemiachange).Hypothermia group C:the vascular of epicardiumexpanded and congested,intercellular edema,andfocal cardiacmyocyte became rarefaction.Conclusion :Mild hypothermia reducedthe myocardial ischemia caused by pituitrin,i mprovedthe heart function.and there was no effect on the dilation of coronary was caused by nitroglycerin.