| ObjectiveRecently with the development of therapy for acute myocardial infarction (AMI) ,we can make the occluded coronary restoring perfusion through throm-bolysis or/and percutaneous coronary intervention ( PCI) , but reperfusion itself may lead to accelerated and additional myocardial injury , this is referred to as the " myocardial ischemia - reperfusion injury" ( MIRI) . The mechanism of MI-RI include oxygen free radial, calcium overloading and so on. Studies aimed at preventing reperfusion injury is one of the hot spot. Scholars are or will be researching pharmacological agents in different experimental models of myocardial ischemia and reperfusion injury,this experiment observed the effects of myocardial ischemia for different duration on reperfusion - induced arrhythmia ( RA) , cardiac performance, malondialdehyde ( MDA) , superoxidedismutase ( SOD ) in rat hearts in vivo, and provide reference for pharmacological experiment in rat in vivo.Methods1. Study objectsHealthy male Wistar rat 60. Weight 200 ~ 250g, provided by animal center of China Medical University.2. Drugs, apparatus and reagentsDrug:0. 9% sodium chloride, 10% hydration chlorine aldehyde, provided by medicament department of the First Affiliated Hospital, China Medical Universi-ty-Apparatus: multifunctional physiological - recording apparatus, respire machine for small animal, press transducer, oxygen bucket, exceeded low temperature refrigeratory, low temperature centrifugal machine, constant temperature case,puddler,tissue muller,721 spectrophotometer,provided by center laboratory of he First Affiliated Hospital, China Medical University.Reagents: MDA reagent box, SOD reagent box, provided by Nanking Jian-ceng biology engineering Graduate School.3. Experiment methodAdult Wistar rats were randomly divided into six groups. The left anterior coronary descending branch was ligated in 0,5 ,10,15,30,60min respectively, then perfusion was restored in 45min. The ECG changes were recorded incessantly. LVSP and LVDP of pre - ischemia and 45min reperfusion were recorded. Myocardial tissue of infarcted zone was scissor to measure malondialdehyde (MDA) content and superoxidedismutase ( SOD ) content.4. Statistical analysisStatistical analysis was performed Windows SPSS 13. 0. Continuous date are presented as mean ± SD. Continous variables with chi - square test or Fisher exact test. A P value <0. 05 was required for statistical significance.Result1. The time that 7-10 min of myocardial ischemia in rat in vivo is the most labile period of inducing ischemia arrhythmia, if reperfused in this time it will induce the most severity reperfusion arrhythmia even death. The occurrence rate of reperfusion arrhythmias ( ventricular tachycardia, VT/ ventricular fiblliation, VF) was 100% after lOmin regional ischemia and 45min reperfusion and the mortality rate was 2% (2/10) in this experiment. The occurrence rate was declined whether the ischemia duration shorter or longer. None of reperfusion arrhythmia occur after lhour occlusion of coronary artery in rat. The relationship between the duration of myocardial ischemia and reperfusion arrhythmia was the style of " bell" .2. Cardiac performance, such as LVSP was decreased and LVDP was increased along with the prolonging of ischemic duration in rat in vivo.3. SOD were decreased along with the prolonging of ischemic duration,on the contrary MDA was increased in rat in vivo.Conclusion1. Reperfusion arrhythmias were more severity following the prolonged duration of ischemia within a limited time in rat in vivo, after a peak time reperfusion arrhythmias were abated and over a limited time reperfusion arrhythmias were not occurrence. Free oxygen radicals were not the most important to reperfusion - induced arrhythmia.2. The decrease of cardiac performance and the production of free oxygen radicals were all changed along with the myocardial ischemic duration in rat in vivo. |
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