Objective    To explore the expressions of ACE/ACE2 in congestive heart failure (CHF) rats after myocardial infarction and the treatment effect of benazepril

an angiotensin converting enzyme inhibitor.     Methods    The rat heart failure model was induced by acute myocardial infarction (AMI) through ligating the left anterior descending coronary artery. One month after operation

rats were randomized to CHF placebo group and benazepril group. Sham-operated rats were used as the control group. Then 8 weeks later the rats were evaluated for hemodynamic parameters

body mass and left ventricular mass index

ACE and ACE2 mRNA expressions by RT-PCR and their protein expressions by immunohistochemical methods.     Results    The mRNA and protein expressions of ACE and ACE2 were increased in CHF placebo group than sham-operation group (P0.01)

and the ratio of ACE/ACE2 was elevated. The hemodynamic parameters of benazepril group improved significantly than CHF placebo group (P0.01). Furthermore

the levels of ACE mRNA and protein of benazepril group decreased significantly (P0.01)

whereas the level of ACE2 mRNA and protein were increased (P0.01)

therefore

the ratio of ACE/ACE2 decreased.     Conclusion    The mRNA and protein expressions of ACE and ACE2 were upregulated in CHF rats

and the ratio of ACE/ACE2 was elevated. Administer of benazepril can downregulate ACE expression and upregulate ACE2 expression

so the ratio of ACE/ACE2 decreases

which might be the another intervention mechanism of the drug.