Gap junction and Na+-H+ exchanger alternations in fibrillating and failing atrium.

Atrial fibrillation (AF) frequently complicates congestive heart failure (CHF). The current study examines whether patients with AF and CHF have alternation in atrial connexins (Cxs) and Na+–H+ exchanger isoform 1 (NHE1). Left atrium was obtained from 29 patients of patients undergoing mitral valve replacement. The connexin 40 (Cx40) protein was significantly higher in AF and sever HF, whereas connexin 43 (Cx43) protein were markedly increased in AF and mild HF but downregulated in the patients with AF and sever HF. NHE activity is significantly greater in AF and sever HF with highest level of NHE1 protein. These change may induce a direct effect on the progressive deterioration of cardiac function in the fibrillation and failure heart.