[Effects of angiotensin converting enzyme inhibitor on the expression of angiotensin converting enzyme 2 in atrium of patients with atrial fibrillation].

Objective: To investigate the expression of angiotensin converting enzyme 2 (ACE2) and the changes treated with angiotensin converting enzyme inhibitor (ACEI), and its signal transduction pathway.

Methods: Atrial tissues were obtained from 47 patients with RHD undergoing cardiac surgery. The mRNA of ACE2 and ACE were semi-qualified by RT-PCR and normalized to the gene beta-actin. Western blot analysis was employed to examine the expressions of ACE2, ACE, ERK1/2 and phosphorylated ERK (pERK1/2). The atrial tissue angiotensin II (Ang II) content was determined by radioimmunoassay detection.

Results: The expression of ACE2 was significantly decreased (P < 0.05), the expression of ACE and pERK1/2 were significantly increased (P < 0.05), and the level of atrial tissue Ang II was significantly increased in patients with chronic atrial fibrillation group (CAF) compared with sinus rhythm group (SR) (P < 0.05). Compared with CAF patients treated without ACEI, the expression of ACE2 significantly increased (P < 0.01), and the relative activity of ERK1/2 significantly decreased (P < 0.05), whereas the expression of ACE and the level of atrial tissue Ang II remained unchanged in CAF patients treated with ACEI.

Conclusions: The study suggested that the dysequilibrium of ACE/ACE2 might play an important role in the process of atrial fibrillation, which may be related to the activation of ERK1/2 pathway. The clinical effect of long-term treatment of ACEI maybe associated with elevated ACE2 expression but not ACE expression.