Transmural L-type calcium current in a pressure-overloaded mouse model with heart failure
- Author:
- No author available
- Journal Title:
- ACTA PHYSIOLOGICA SINICA
- Issue:
- 1
- DOI:
- 10.3321/j.issn:0371-0874.2007.01.005
- Key Word:
- 动作电位;L-型钙电流;心衰;跨壁电生理异质性;小鼠
Abstract： 为了观察正常和心衰时心内膜下和心外膜下心肌细胞L-型钙电流(ICa-L)的差别,我们采用主动脉弓狭窄的方法建立小鼠压力超负荷性心衰模型,采用全细胞膜片钳技术记录了正常、主动脉狭窄(band)及假手术对照(sham)组动物左心室游离壁内、外膜下心肌细胞的动作电位时程(action potential duration,APD)和ICa-L°结果显示:(1)与sham组同龄的正常小鼠左心室心内膜下细胞动作电位复极达90%的时程(APD90)为(38.2±6.44)ms,较心外膜下细胞的APD90(15.67±5.31)ms明显延长,二者的比值约为2.5∶1;内膜下细胞和外膜下细胞ICa-L密度没有差异,峰电流密度分别为(-2.7±0.49)pA/pF和(-2.54±0.53)pA/pF;(2)Band组内、外膜下细胞的动作电位复极达50%的时程(APD50)、APD90均较sham组显著延长,尤以内膜下细胞延长突出,分别较sham组延长了400%和360%,内、外膜下细胞APD90的比值约为4.2∶1;(3)与sham组相比,band组内膜下细胞ICa-L密度显著减小,在+10 mV～+40 mV的4个电压下分别降低了20.2%、21.4%、21.6%和25.7%(P＜0.01),但其激活电位、峰电位和翻转电位没有改变;band组外膜下细胞的ICa-L密度与同期sham组相比无明显变化;band组钙通道激活、失活及复活的动力学特征与sham组相比没有改变.以上结果提示,生理状态下小鼠左心室内、外膜下细胞ICa-L密度不存在明显差别,提示ICa-L与APD跨壁异质性的产生无关;心衰时左心室内、外膜下细胞APD明显延长,以内膜下细胞延长尤为突出,内膜下细胞ICa-L密度明显减少,而外膜下细胞ICa-L密度无明显改变,这种ICa-L的非同步变化在心衰时可能起到对抗APD延长、减少复极离散度的有益作用.
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