BACKGROUND: Interaction and dynamic balance of matrix metalloproteinases and tissue inhibitory factor in atrial is closely related with the occurrence maintenance of atrial fibrillation (AF).
OBJECTIVE: To investigate the matrix metalloproteinase-9 (MMP-9) and tissue inhibitor-1 of metalloproteinase gene expression in atrial and to evaluate the influence of MMP-9 and tissue inhibitor-1 (TIMP-1) expression on AF and fibrosis.
METHODS: The chronic rapid atrial pacing was used to establish the persistent AF dog model and the sham-operated group was seted. Masson three color staining was used to determine the stage of fibrosis, the expression the left atrial MMP-9 mRNA and TIMP-1 mRNA level was detected through reverse transcriptase polymerase chain reaction. The level of protein expression was determined by Western Blot.
RESULTS AND CONCLUSION: Compared with sham-operated group, the degree of fibrosis and collagen volume fraction (CVF) in persistent AF model group was increased obviously (P < 0.01), and the expression of MMP-9 mRNA was increased obviously as well as its protein expression (P < 0.01). The level of TIMP-1 mRNA and protein expression was decreased obviously       (P < 0.01). The imblanced regulation of gene expression betewwn MMP-9 and TIMP-1 of atrial fibrillation, heighten of MMP-9 activity and reduce of TIMP-1 activity may influence collagen metabolism, promoting or inhibiting the myocardial fibrosis, it is one of the molecular mechanism that cause the reconstruction of atrial structure in atrial fibrillation.