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Objective: To investigate benazepril preconditioning on cold stimulation of myocardial infarction cardiac function and possible mechanisms. Methods: 30 male SD rats were divided into normal group after myocardial infarction (GN group , n = 10), at room temperature is set to 26 ℃; cold after myocardial infarction group (GC group , n = 10), set to cold stimulation 4 ℃; benazepril cold pretreatment group after myocardial infarction (BC group , n = 10). 4 days of treatment the rats cardiac function was measured by echocardiography , and specimens from myocardial infarct size measured specimen , HE staining showed morphological changes in myocardium , immunohistochemical detection of apoptosis -related protein expression of Bim , western blot detection of Bim, caspase- 3 ERK5 (extracellular-regulated kinase 5, extracellular signal-regulated kinase 5 ) and ERK5 phosphorylation levels (p-ERK5). Results : (1) GC group ejection fraction (0.594 ± 0.042) and fractional shortening (0.265 ± 0.030) was significantly lower than the GN group (0.664 ± 0.040,0.337 ± 0.046), GC group, left ventricular end systolic diameter (0.486 ± 0.029 ) and end-diastolic diameter (0.772 ± 0.033) was significantly greater than the GN group (0.391 ± 0.022,0.648 ± 0.040), while the BC group, these indicators were (0.704 ± 0.036,0.379 ± 0.042,0.384 ± 0.030,0.613 ± 0.070), significantly better than the GC group . (2) GC group Bim, caspase-3 expression (0.375 ± 0.047,0.662 ± 0.007) was significantly higher than GN group (0.236 ± 0.013,0.306 ± 0.009), BC group Bim and caspase-3 expression (0.222 ± 0.018,0.285 ± 0.020 ) , significantly lower than the GC group . (3) BC group, p-ERK5 expression (0.728 ± 0.008) was significantly higher than the GC group (0.274 ± 0.021). Conclusion: cold stimulation can worsen rat model of myocardial infarction cardiac function , increased Bim and caspase-3 expression, whereas pretreatment by benazepril can improve heart function , may be associated with reduced Bim, caspase-3 expression and ERK5 signaling pathway activation.
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