Development of the fast sodium current in early embryonic chick heart cells.
Development of the fast sodium current in early embryonic chick heart cells.
复制标题
早期胚胎鸡心脏细胞中快速钠电流的发展。
DOI：
10.1007/bf01872836
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
DeHaan,RL
中科院分区：
文献类型：
--
作者：
Fujii,S;AyerJr,RK;DeHaan,RL
从2、3、4、7日龄鸡胚心脏分离单个心室细胞，体外培养6 ~ 28小时，取直径13 ~ 18 μm、输入电容5 ~ 10 pF的圆形细胞，分析快钠电流（INa）。用膜片电极在全细胞钳形结构中观察了INa的电压依赖性和动力学，结果表明，INa在2d的一半以上细胞中存在，3d、4d和7 d的细胞中均存在。电流在激活动力学、电压依赖性和河豚毒素（TTX）敏感性方面与年龄和培养条件没有系统性差异。在2d和7 d阶段之间，电流失活速率增加了一倍，通道密度增加了约8倍。TTX在0.5 ~ 1.0nM的半数有效浓度下，可阻断INa在所有实验阶段的表达。我们的结论是缺乏钠依赖性的动作电位upstroke的第二天的发展结果从相对去极化水平的舒张电位，并未能激活小的可用兴奋性钠电流。从Ca到Na的依赖性的上升冲程在第三至第七天的孵化结果的变化，部分从舒张期电位在此期间的负移，部分从可用的Na电导的增加。
Single ventricle cells were dissociated from the hearts of two-, theree-, four-, or seven-day-old chick embryos, and were maintained in vitro for an additional 6 to 28 hr. Rounded 13 to 18 μm cells with input capacitance of 5 to 10 pF were selected for analysis of fast sodium current (INa). Voltage dependence, and kinetics ofINawere applied with patch electrodes in the wholecell clamp configuration.INawas present in over half of the 2d, and all 3d, 4d and 7d cells selected. The current showed no systematic differences in activation kinetics, voltage dependence, or tetrodotoxin (TTX) sensitivity with age or culture condition, Between the 2d and 7d stages, the rate of current inactivation doubled an channel density increased about eighfold. At all stages tested,INawas blocked by TTX at a half-effective concentration of 0.5 to 1.0 nM. We conclude that the lack of Na dependence of the action potential upstroke on the second day of development results from the relatively depolarized level of the diastolic potential, and failure to activate the small available excitatory na current. The change from Ca to Na dependence of the upstroke during the third to the seventh day of incubation results partly from the negative shift of the diastolic potential during this period, and in part from the increase in available Na conductance.