Objective: To investigate the relationship between the alternations in the expression and distribution of connexin 40 (Cx40) and connexin 43 (Cx43) and atrial fibrillation (AF) in patients with rheumatic heart disease.
Methods: Biopsy was conducted to take specimens of right atrial appendage (RAA) from 32 patients with rheumatic heart disease, 21 with AF and 11 with sinus rhythm (SR) during valve replacement. The protein levels of Cx40 and Cx43 were examined by immunoconfocal microscopy and Western blotting. The former was also used to observe the distribution of Cx40 and Cx43 double-labeled with antibodies against Cx40 and Cx43.
Results: Immunoconfocal microscopy showed that the relative expression level of Cx40 protein in the specimens of RAA in the chronic AF group was (0.67 microm(2)/ microm(3) +/- 0.09 microm(2)/ microm(3)), significantly lower than that in the SR group (1.45 microm(2)/ microm(3) +/- 0.16 microm(2)/ microm(3)) (P < 0.01). There was no significant difference in the expression of Cx43 protein between the two groups. Distributed inhomogeneously, Cx40 and Cx43 were mainly located at the side to side interconnections, instead of being confined to the intercalated discs, as observed in the patients with SR. The results of Western blotting were similar to those of immunoconfocal microscopy.
Conclusion: The reduction and redistribution of Cx40 and Cx43 contribute to initiation and persistence of AF in patients with rheumatic heart disease.