Kinetic analysis of single sodium channels from canine cardiac Purkinje cells.
Kinetic analysis of single sodium channels from canine cardiac Purkinje cells.
复制标题
犬心脏浦肯野细胞单钠通道的动力学分析。
DOI：
10.1085/jgp.95.3.411
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Fozzard,HA
中科院分区：
文献类型：
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作者：
Scanley,BE;Hanck,DA;Chay,T;Fozzard,HA
在10-13℃条件下，单犬心脏浦肯野细胞细胞贴附膜片记录单钠通道事件，选取4个含2 - 4个通道的膜片和1个含1个通道的膜片进行定量分析。通道在阈值附近表现出明显的重开行为，重开数量随着去极化而急剧下降。平均通道打开时间是电压的双相函数，最大值（1-1.5 ms）出现在-50和-40 mV之间，在超极化水平较高和较低时，其值较低。无开口失活在阈值附近也很突出，这种情况随着去极化而减少。等待时间分布和打开的概率显示出与全细胞电流研究预期的电压和时间依赖性。利用直方图分析和极大似然法估计动力学参数，对结果进行了五态马尔可夫动力学模型分析。模型拟合的动力学参数与GH3垂体细胞相似（Horn， R., and C. A. Vandenberg. 1984）。神经母细胞瘤细胞与神经母细胞瘤细胞的关系（生物医学工程学报，84:505-534）。神经科学杂志。7:418-431)。直方图和最大似然分析表明，心脏钠电流的电压依赖性主要体现在其激活行为上，而失活表现为适度的电压依赖性。
Single sodium channel events were recorded from cell-attached patches on single canine cardiac Purkinje cells at 10-13 degrees C. Data from four patches containing two to four channels and one patch with one channel were selected for quantitative analysis. The channels showed prominent reopening behavior at voltages near threshold, and the number of reopenings declined steeply with depolarization. Mean channel open time was a biphasic function of voltage with the maximum value (1-1.5 ms) occurring between -50 and -40 mV and lower values at more and at less hyperpolarized levels. Inactivation without opening was also prominent near threshold, and this occurrence also declined with depolarization. The waiting time distributions and the probability of being open showed voltage and time dependence as expected from whole-cell current studies. The results were analyzed in terms of a five-state Markovian kinetic model using both histogram analysis and a maximum likelihood method to estimate kinetic parameters. The kinetic parameters of the model fits were similar to those of GH3 pituitary cells (Horn, R., and C. A. Vandenberg. 1984. Journal of General Physiology. 84:505-534) and N1E115 neuroblastoma cells (Aldrich, R. W., and C. F. Stevens. Journal of Neuroscience. 7:418-431). Both histogram and maximum likelihood analysis implied that much of the voltage dependence of cardiac Na current is in its activation behavior, with inactivation showing modest voltage dependence.