Study on expression of mineralocorticoid receptor in human atria during atrial fibrillation

Objective To investigate the mRNA and protein expression of mineralocorticoid receptor (MR) in patients with atrial fibrillation.Methods Twenty-five patients with rheumatic heart valve disease,12 in sinus rhythm and 13 in chronic atrial fibrillation (≥6 months),underwent transthoracic echocardiography and right and left atrial lateral wall tissue samples were obtained from these patients during mitral/aortic valve replacement operation.Reahime quantitative PCR and Western blot were used to determine the mRNA and protein expression of MR in atria specimens.The distribution of MR in human atria was analyzed by specific immunohistochemical staining.Results The left atrial diameters increased markedly in atrial fibrillation group compared with that in sinus rhythm group (P0.01).And the results showed that the level of mRNA and protein of MR were increased significantly in atrial fibrillation group compared with those in sinus rhythm group (P0.01 or 0.05),whereas the expression of mRNA and protein of MR were found to be no difference between left atria and right atria both in fibrillation and sinus groups (all P0.05).The special immunohistochemical staining demonstrated that MR was abundant in the human atrial myocardium and MRs were located mainly in the cytoplasm of atrial cells,which were more evident in atrial fibrillation group than those in sinus rhythm group.Conclusion These findings suggested that MRs were upgulated in atrial fibrillation and aldosterone antagonists may be effective in treating atrial fibrillation.