目的观察比索洛尔对容量超负荷心衰大鼠左室心肌细胞内向整流钾电流((I_(K1))的影响。方法成年雄性SD大鼠(180-200 g)随机分为假手术组、心衰组和比索洛尔干预组,采用腹主动脉-下腔静脉穿刺造瘘法制作容量超负荷心衰模型。术后8周,比索洛尔干预组给予比索洛尔(1 mg/kg,1次/d)灌胃,干预4周后,检测血清脑钠肽(BNP)及超声心动图以评价心功能。急性酶解法分离大鼠左室心肌细胞,采用全细胞膜片钳技术记录动作电位及I_(K1)电流,并绘制I-V曲线。结果心衰组与假手术组大鼠比较,心功能明显下降,血清BNP水平(pmol/L)明显升高(1 562.89±153.26 vs 225.57±63.62,P<0.01),动作电位时程(APD,ms)延长(APD_(90):324.85±21.66 vs 137.80±15.24,P<0.01),I_(K1)电流密度减小(-140 m V:-23.20±2.10 vs-35.55±2.78,P<0.01)。比索洛尔干预可明显改善心功能,缩短APD,增加I_(K1)电流密度(-140 m V:-27.16±2.62vs-23.20±2.10,P<0.01)。结论比索洛尔干预可改善慢性心衰大鼠的心功能,增加I_(K1)电流密度。
Remodeling of ion channels is an important mechanism of arrhythmia induced by heart failure （HF）. We investigated the expression of potassium channel encoding genes in the ventricles of rabbit established by volumeoverload operation followed with pressure-overload. The reversible effect of these changes with bisoprolol was also evaluated. The HF group exhibited left ventricular enlargement, systolic dysfunction, prolongation of corrected QT interval （QTc）, and increased plasma brain natriuretic peptide levels in the HF rabbits. Several potassium channel subunit encoding genes were consistently down-regulated in the HF rabbits. After bisoprolol treatment, heart function was improved significantly and QTc was shortened. Additionally, the mRNA expression of potassium channel subunit genes could be partially reversed. The down-regulated expression of potassium channel subunits Kv4.3, Kv1.4, KvLQT1, minK and Kir 2.1 may contribute to the prolongation of action potential duration in the heart of rabbits induced by volume combined with pressure overload HF. Bisoprolol could partially reverse these down-regulations and improve heart function.
Xi LiTingzhong WangKe HanXiaozhen ZhuoQun LuAiqun Ma
