Chloride channels ClC-1 and ClC-2 gene expression in human atrial tissue and their relationship with atrial fibrillation

Objective To investigate gene expression of chloride channel ClC-1 and ClC-2 in human atrial tissue and their relationship with atrial fibrillation(AF).Methods Right atrial appendage specimens were obtained from 33 patients with chronic AF(CAF group),7 with paroxysmal AF(PAF group) and 31 matched controls in sinus rhythm(SR group) who underwent the open-heart surgery.Semi-quantitative polymerase chain reaction(RT-PCR) was used to examine the mRNA expression of ClC-1 and ClC-2 channels in atrial tissue.Results ①There were chloride channels ClC-1 and ClC-2 gene expressing in human atrial tissue.②The content of ClC-1 mRNA in CAF group was significantly higher than that in SR group(1.25±0.18 vs 1.01±0.13,P0.001).There was no significant difference between PAF group(1.05±0.22) and SR group although the content of ClC-1 mRNA was slightly higher than that in SR group(P0.05).The significant difference was observed between CAF group and PAF group(P0.01).ClC-1 expression at mRNA level was positively correlated with left atrial dimension and AF duration[(r=0.344,P=0.003)(r=0.405,P0.001)].③ The content of ClC-2 mRNA in CAF group was significantly higher than that in SR group(1.26±0.13 vs 1.03±0.14,P0.001),There was no significant difference between PAF group(1.04±0.15) and SR group(P0.05).The significant difference was observed between CAF group and PAF group(P0.01).ClC-2 expression at mRNA level was positively correlated with left atrial dimension and AF duration[(r=0.441,P0.001)(r=0.331,P=0.005)].Conclusions Increased gene expression of chloride channel ClC-1 and ClC-2 may serve as the molecular basis of atrial tissue electrical remodeling in patients with AF.