Changes of microRNA-1 and microRNA-21 in human atrial fibrillation

Objectives To investigate changes of microRNA- 1(miR-1) and microRNA-21(miR-21) expressions in human atrial fibrillation(AF).Methods Right atrial appendages were obtained from 12 rheumatic valvular heart disease patients with sinus rhythm(SR)and 14 patients with chronic AF.Quantitative real time polymerase chain reaction(qRT-PCR) was applied to assess expressions of miR-1 and miR- 21.Immunohistochemistry was used to evaluate Kir2.1 expression and masson staining was used to estimate collagen deposition.Results Expressions of miR-1 was decreased (relative expression:0.68±0.09 vs.1.76±0.15,PmiR-21 was increased(relative expression:2.23±0.31 vs.0.94±0.24 vs. 0.043±0.005 vs.8.3±0.01;PmiR-l was negatively correlated to that of left atrium diameters(r=-0.47,P=0.02).Expression of miR-21 was positively correlated to collagen content (r=0.45,P<0.01).Conclusions Expression of miR-1 was down-regulated in AF patients,which may be associated with the increase in Kir2.1.miR-21 level was significantly up-regulated, which may contribute to the increase in collagen content in the atrium.