Background and Aims The aim of this study was to explore the expression changes of myocardial APN in acute myocardial infarction (AMI) rats, changes of serum APN, and the significance of Bisoprolol intervention.

Methods AMI rat model was established for the purposes of this study and was used for analysis of serum APN as determined by ELISA. Expression changes of myocardial APN mRNA in AMI rats were determined via RT-PCR and expression changes of myocardial APN protein were determined by the way of immunohistochemistry.

Results Serum APN concentration and APN protein expression of the myocardium decreased significantly in the AMI groups compared with the sham operation group, with the lowest serum APN and APN protein expression on day 7 after AMI. On days 7 and 10 after AMI, the expression of myocardial APN mRNA in the AMI groups decreased significantly compared with the sham operation group. However, the APN mRNA increased on day 10 compared with that on day 7. Notably, there was an increase in levels of serum APN and myocardial APN expression after Bisoprolol intervention.

Conclusions The expression of myocardial APN and serum APN decreased in AMI rats. APN may be an important protective factor against AMI. Bisoprolol can also protect against AMI due to its increasing APN expression.