亚低温治疗实验性脑梗死时对心脏的影响

Effects of mild hypothermia on heart of rats with focal brain ischemia

目的 研究全身亚低温治疗实验性脑梗死时对心脏的影响。方法 5 8只Wistar大鼠分成对照组 (n =10 )、常温组 (n =2 4)和亚低温组 (n =2 4) ,采用线栓法制作大脑中动脉 (MCA)梗死模型。监测ECG ,测定术后 12h心肌高能磷酸化合物 (ATP、ADP、AMP)、能量储备 (EC)值和心肌超微结构改变。结果 缺血后 12h时常温组和亚低温组大鼠心肌ATP、ADP、EC均低于对照组 (P <0 .0 1) ,但亚低温组的ATP和EC却高于常温组 (P <0 .0 1) ;常温组和亚低温组异常ECG发生率无明显差异 (P >0 .0 5 ) ;但亚低温组的心率明显低于常温组 (P <0 .0 1) ,有 3只大鼠的心率低于 15 0次 /min ;超微结构显示常温组和亚低温组心肌均有缺血性损伤 ,但亚低温组的损伤较常温组轻。结论 全身亚低温治疗实验性脑梗死时能改善心肌的能量储备 ,减轻脑梗死引起的心肌缺血 ,不会增加ECG异常的发生率 。

Objective To investigate the effects of systemic mild hypothermia on heart. Methods Fifty-eight Wistar rats were divided randomly into three groups: control group (n=10), normal thermic group (n=24) and mild hypothermic group (n=24). After the model of middle cerebral artery occlusion (MCAO) was made, electrocardiograph (ECG) was used to monitor the cardiac function of the animals. The changes of myocardial high-energy phosphates (ATP,ADP,AMP) and energy charge (EC) were evaluated after 12 hours of ischemia, and the myocardial ultrastructure observed. Results Compared with the control group, the ATP, ADP and EC in the normal thermic group and mild hypothermic group were lower after 12 hours of ischemia (P<0.01), while the ATP, EC in mild hypothermic group were higher than those in normal thermic group (P<0.010). The heart rate of mild hypothermic group was lower than normal thermic group (P<0.01). There was no significant difference between the mild hypothermic and the normal thermic groups with regard to the incidence of abnormal ECG. The ischemic myocardial damage in the rat of mild hypothermic group was milder than that of normal thermic group. Conclusion Systemic mild hypothermia can improve myocardial EC and ameliorate the ischemic myocardial damage, result in no severe electrocardiographic abnormality. Thus it can exert favourable effect for preserving cardiac function in rat after cerebral ischemic injury.