Enalapril Decreased Inducible Atrial Fibrillation in Old Rats / 天津医药

ABSTRACT

Objective: To study the effect of enalapril on inducible atrial fibrillation(AF) in old rats. Methods: Old male Wistar rats were randomly divided into control group(n = 12) and experimental group(n = 13). Rats in control group were fed routinely. Rats were fed with enalapril besides normal diet in experimental group for three months. Rats were then anesthetized, thoracotomy was performed and pericardium was opened to expose heart. Right atrium effective refractory period(ERP) was measured. Sinus conduction time (SCT) and sinus recovery time (SRT) were measured for evaluating sinus function. Interatrial conduction time(IACT) and atrium response to burst pacing were evaluated in vivo. Plasma angiotensinⅡ level and atrial tissue angiotensinⅡ level were determined by radioimmunoassay. Sections were cut from the tissue of atrium and stained with Masson trichrome. The ratio of the area occupied by interstitial to the total area was measured. Results: Contrast to control group,IACT and SRT were shorter in experimental group(P ＜ 0.01 and P ＜ 0.05 respectively). AF were induced in 9 rats in control group and 4 rats in experimental group(P ＜ 0.05). AngiotensinⅡconcentration was significantly decreased in right and left atrium tissues of experimental group compared with that in control group(P ＜ 0.01). A significant decrease in interstitial atrial fibrosis was presented in experimental group compared with that of control group(P ＜ 0.01). Conclusion: Inducible atrial fibrillation rate was decreased in old rats after treatment with enalapril. This effect maybe resulted from the inhibited local atrium renin-angiotensin system and improved sinus node function by enalapril.