A pilot study of using spurt,repeated cryoinjury and off-ventilator to establish rat model of acute myocardial infarction / 第三军医大学学报

ABSTRACT

Objective To explore a new method of establishing rat model of acute myocardial infarction by off ventilator support,spurt and repeated cryoinjury.Methods Sixty Wistar rats with male and female in half were randomized into three experimental groups according to cryoinjury time with 20 rats in each group15-second group(cryoinjury for 5 s each time,three times in total),25-second group(5 s each time,five times in total)and 40-second group(5 s each time,eight times in total).The heart was exposed through a 1.0-to 1.5-cm left lateral thoracotomy.Cryoinjury of the LV free wall(LVFW)was performed by applying for 5 s a round copper probe of 6-mm in diameter immersed in liquid nitrogen for 5 min to reach-190 ℃,then the thoracic cavity was closed immediately.When the rats' breath restored,the cryoinjury of the LVFW in situ was repeatedly to ensure a transmural injury according to the protocol.The survival rate during operation and in 28 days after operation was observed.Also infarct size was observed by heart pathological section stained with Masson's trichrome on day 28 after operation.Results Infarct size in all three groups was larger than 20% signified by transmural injury,and completely myocardiolysis and distinct infarct boundary were observed.The survival rate was 16/20 in 15-second group,5/20 in 40-second group(P0.05 vs 15-second group and 40-second group).The infarct size in 40-second group was larger than the other two groups(standard deviation10.564 4% vs 5.192 6%,6.496 0% in 15,25-second group,respectively)and its survival rate was lowest.The procedure of 25-second group was more complicated and had a tendency of higher death rate than that in 15-second group.Conclusion Using spurt,repeated ultra low temperature cryoinjury for 15 s may be an ideal method to establish the rat model of acute myocardial infarction.