The Protective Effects Of Benazepril On The Cardiac Dysfunction Induced By AMI And Cold Stress In Rats

AIM:To explore the effects of benazepril on the cardiac function under cold stress in rats with acute myocardial infarction (AMI) and the potential mechanisms.METHODS:Thirty male SD rats were randomly divided into 3 groups:AMI+normal temperature group (GN group, n=10,26℃), AMI+cold stress group (GC group, n=10,4℃), benazepril preconditioning+AMI+cold stress group (BC group, n=10, 4℃).4 days after the treatments, the cardiac function of the rats was measured by echocardiography, and the heart samples were obtained to measure the infarction size. The morphological changes were evaluated by HE staining, expression of Bim was measured by immunohistochemistry and Western blot, moreover, expressions of caspase 3,ERK5 and p-ERK5 were evaluated by Western blot.RESULTS:(1) LVEF, FS of GC group (0.594±0.042,0.265±0.030) were significantly lower than that of GN group (0.664±0.040,0.337±0.046), LVSD and LVDD of GC group (0.486±0.029,0.772±0.033) were significantly higher than that of GN group (0.391±0.022,0.648±0.040), while those indexes of BC group (0.704±0.036, 0.379±0.042,0.384±0.030,0.613±0.07) were much better than GC group.(2)Bim and caspase-3 expressions were significantly higher in GC group(0.375±0.047,0.662±0.007) than that of GN group(0.236±0.013,0.306±0.009), and benazepril preconditioning could significantly down-regulate the increased Bim and caspase-3 expressions (0.222±0.018,0.285±0.020).(3)p-ERK5 expression was significantly higher in BC group(0.728±0.008) compared to GC group (0.274±0.021).CONCLUSIONS:Cold stress may deteriorate cardiac function of rats suffered from AMI, increase the expressions of Bim and caspase-3. Benazepril preconditioning may improve cardiac function of rats with AMI under cold stress,and this effect may be associated with reduction of Bim and caspase-3 and activation of ERK5 pathway..