Abstract:

Objective To investigate the effects of simvastatin on neural and electrical remodeling of atria in rats with myocardial infarction. Methods Twenty-two SD rats were randomly divided into myocardial infarction group (n=11) and simvastatin group (n=11) after successful establishment of model of myocardial infarction, and another 11 rats were served as sham operation group which were not ligated in the same part of the heart. Four weeks after operation, echocardiographic and electrophysiologic examinations were conducted, immunohistochemistry was used to determine the distribution and density of growth-associated protein-43 (GAP-43) and tyrosine hydroxylase (TH) positive staining nerve fibers, and expression of nerve growth factor (NGF) mRNA was detected by Real-Time PCR. Results Compared with sham operation group, the expression of NGF mRNA and density of positive staining nerve fibers were significantly higher, the diameter of left atria was much longer, the ejection fraction was significantly lower, the atrial effective refractory period (AERP) was much shorter, and the prevalence of atrial tachyarrhythmia (AT) was significantly higher in myocardial infarction group (P<0.05 for all). Compared with myocardial infarction group, the expression of NGF mRNA and density of positive staining nerve fibers were significantly lower, the diameter of left atria was much shorter, the ejection fraction was significantly higher, AERP was much longer, and the prevalence of AT was significantly lower in simvastatin group (P<0.05 for all). However, there were still significant differences in these parameters between simvastatin group and sham operation group (P<0.05). Conclusion Simvastatin can effectively improve neural and electrical remodeling of atria in rats with myocardial infarction, and may play a potential role in the prevention of AT, the mechanism of which may be associated with the down-regulation of expression of NGF.

Key words: simvastatin, myocardial infarction, nerve remodeling, electrical remodeling, atrial tachyarrhythmias