Characterization of ion channels on the surface membrane of adult rat skeletal muscle.
Characterization of ion channels on the surface membrane of adult rat skeletal muscle.
复制标题
成年大鼠骨骼肌表面膜离子通道的表征。
DOI：
10.1016/s0006-3495(91)82340-2
复制
发表时间：
1991
影响因子：
3.4
通讯作者：
Betz,WJ
中科院分区：
文献类型：
--
作者：
Chua,M;Betz,WJ
应用膜片钳技术观察了大鼠趾短屈肌肌纤维表面膜上存在的通道。139根纤维中有85根具有新型通道，排除了氯离子、硫酸根和羟乙磺酸根阴离子，氯离子与钠的渗透率比小于0.05。对阳离子的选择性顺序为Na+ = K+ = Cs+> Ca++ = Mg++> N-甲基-D-葡糖胺。该通道长时间保持关闭，并具有约320 pS的大电导，在约34 pS的水平具有几个亚电导状态。通道活性不依赖于电压，肌纤维中阳离子的反转电位约为0 mV，导致通道表现为生理泄漏电导。电压激活钾通道存在于65个细胞贴附的补丁，并有电导大多为6，12和25 pS。钾通道的电压敏感性与延迟整流电流的电压敏感性一致。只有三个补丁含有氯离子通道。尽管已知骨骼肌的高氯离子电导，但氯离子通道的稀缺性表明大多数氯离子通道必须位于横管系统中。
The channels present on the surface membrane of isolated rat flexor digitorum brevis muscle fibers were surveyed using the patch clamp technique. 85 out of 139 fibers had a novel channel which excluded the anions chloride, sulfate, and isethionate with a permeability ratio of chloride to sodium of less than 0.05. The selectivity sequence for cations was Na+ = K+ = Cs+ greater than Ca++ = Mg++ greater than N-Methyl-D-Glucamine. The channel remained closed for long periods, and had a large conductance of approximately 320 pS with several subconductance states at approximately 34 pS levels. Channel activity was not voltage dependent and the reversal potential for cations in muscle fibers of approximately 0 mV results in the channel's behaving as a physiological leakage conductance. Voltage activated potassium channels were present in 65 of the cell attached patches and had conductances of mostly 6, 12, and 25 pS. The voltage sensitivity of the potassium channels was consistent with that of the delayed rectifier current. Only three patches contained chloride channels. The scarcity of chloride channels despite the known high chloride conductance of skeletal muscle suggests that most of the chloride channels must be located in the transverse tubular system.