The permeability of the sodium channel in Myxicola to the alkali cations.
The permeability of the sodium channel in Myxicola to the alkali cations.
复制标题
Myxicola 中钠通道对碱金属阳离子的渗透性。
DOI：
10.1085/jgp.68.3.327
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发表时间：
1976-09
影响因子：
3.8
通讯作者：
Goldman, L
中科院分区：
文献类型：
--
作者：
Ebert, G A;Goldman, L
相对渗透性的碱金属阳离子进行了测定，从逆转电位（VRev），为钠通道的内部灌注电压钳位Myxicola巨大的轴突。PLi/PNa和PK/PNa分别为0.94和0.076。Rb和Cs是不可测量的渗透性。在300倍的内部Na浓度范围内，恒定场方程很好地描述了VRev与内部Na活性的关系。与鱿鱼轴突上的发现一致，发现当内部灌注液的K含量降低时，PK/PNa增加（相当于用TMA进行等价替换）。内源性Rb和Cs也降低PK/PNa。内部K、Rb和Cs在增加Na通道的Na选择性方面的有效性顺序为Cs大于Rb大于或等于K。外部Li增加PK/PNa，但这可能是由于内部LiF的形成。可能的是，物质不必穿过通道以影响选择性过滤器。证据表明，Na通道的选择性可能是更高的Na在完整的灌注巨轴突相比。结果表明，信道选择性特性并不只是反映信道的某些固定结构特征，而是反映了选择性滤波器的不稳定性。
Relative permeabilities to the alkali cations were determined, from the reversal potential (VRev), for the Na channel of internally perfused voltage-clamped Myxicola giant axons. PLi/PNa and PK/PNa are 0.94 and 0.076, respectively. Rb and Cs are not measurably permeant. VRev vs. the internal Na activity was well described by the constant field equation over a 300-fold range of internal Na concentrations. In agreement with findings on squid axons, the PK/PNa was found to increase when the K content of the internal perfusate was reduced (equivalent per equivalent substitution with TMA). Internal Rb and Cs also decreased the PK/PNa. The order of effectiveness of internal K, Rb, and Cs in increasing the Na selectivity of the Na channel was Cs greater than Rb greater than or equal to K. External Li increases the PK/PNa but this may be due to the formation of LiF internally. It may be that substances do not have to traverse the channel in order to affect the selectivity filter. Evidence is presented which suggests that the selectivity of the Na channel may be higher for Na in intact as compared to perfused giant axons. It was concluded that the channel selectivity properities do not reflect only some fixed structural features of the channel, but the selectivity filter has a labile organization.