Expression of angiotensin II receptors in human left and right atrial tissue in atrial fibrillation with and without underlying mitral valve disease

Abstract

ObjectivesWe postulated a change of angiotensin II receptor subtype expression in patients with lone atrial fibrillation (AF) and AF with underlying mitral valve disease (MVD) both compared with sinus rhythm (SR). BackgroundAtrial fibrillation is a progressive disease associated with electrical and structural remodeling. Angiotensin II (ANGII) is involved in the process of myocardial remodeling. Actions of ANGII are mediated by ANGII receptor subtypes 1 and 2 (AT1and AT2). MethodsLeft atrial (LA) and right atrial (RA) tissue samples were obtained from patients with AF or SR with or without underlying MVD. The AT1and AT2protein levels were measured by quantitative Western blotting techniques. ResultsThe AT1protein level in the LA was significantly increased in patients with AF (all forms) compared with SR (p < 0.05), whereas AT2expression was not significantly altered. Comparison of the subgroups revealed a similar increase of AT1in both paroxysmal AF and chronic AF with or without MVD. Additionally, investigations of ANGII receptor subtypes in the RA did not exhibit any significant changes either in AT1or in AT2in patients with AF versus SR. Underlying MVD did not significantly affect AT2receptor subtype expression in LA. ConclusionsAtrial fibrillation is associated with an up-regulation of AT1in LA, but not in RA, and did not appear to influence the AT2expression in the atrium. Because we found an enhanced expression of AT1in the LA, we conclude that AT1might be involved in the pathogenesis of AF in the LA.