Find in Library

<p><i>Aim:</i> To elucidate the protective effects of Matrine on atrial fibrillation (AF) induced by electric pacing in mice and underlying molecular and ion channel mechanisms.</p><p><i>Methods:</i> AF was introduced by electric pacing in mice and the incidence and duration of AF were evaluated. Functional expression of M₃ receptor (M₃-R) and Cav1.2 were explored by western and Real-time PCR, action potential (AP) and the density of (I_KM3) L-type calcium channel (I_Ca-L) were both recorded using whole-cell patch in isolated atrial cardiomyocytes.</p><p><i>Results:</i> In control group, incidence and duration of AF induced by electric pacing were 50 ± 17% and 3.68 ± 1.84 s, respectively; after application of carbachol 50 µg/kg both incidence and duration of AF were significantly increased to 86 ± 24% and 65.2 ± 29.0 s. Compared with control group, pretreatment of Matrine for 15 days significantly reduced AF incidence and duration in dose-dependent manner. Atrial membrane-protein expression of M₃-R was decreased and membrane Cav1.2 expression was up-regulated. In single Matrine-treated atrial cardiomyocyte the density of I_KM3 was significantly decreased by 39% as well compared with control group, <i>P</i> < 0.05, whereas, I_Ca-L density of atrium was increased by 40%.</p><p><i>Conclusion:</i> These data demonstrated at the first time that the anti-AF effects of Matrine may due, at least in part, to down-regulation of I_KM3 density and M₃-R expression and up-regulation of I_Ca-Ldensity and α1C/Cav1.2 expression.</p>