Density of sodium channels in mammalian myelinated nerve fibers and nature of the axonal membrane under the myelin sheath.
Density of sodium channels in mammalian myelinated nerve fibers and nature of the axonal membrane under the myelin sheath.
复制标题
哺乳动物有髓神经纤维中钠通道的密度和髓鞘下轴突膜的性质。
DOI：
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发表时间：
1977
影响因子：
11.1
通讯作者：
R. Rogart
中科院分区：
文献类型：
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作者：
J. M. Ritchie;R. Rogart
通过测量[3 H]石房蛤毒素与兔坐骨神经的结合，估计了哺乳动物有髓纤维中钠通道的密度。与完整和均质化神经的结合由线性、非特异性组分和代表与钠通道结合的可饱和组分组成。完整神经中的最大饱和结合容量为19.9 +/- 1.9 fmol-mg湿-1;平衡解离常数Kt为3.4 +/- 2.0 nM。均质化几乎没有差异，最大结合容量为19.9 +/- 1.5 fmol-mg湿-1，Kt = 1.3 +/- 0.7 nM。这些值对应于每个节点约700，000个钠通道的密度-即，每mum 2结膜约有12，000个。从完整和均质制剂中最大饱和结合容量值之间的差异来看，考虑到其估计值的统计不确定性，似乎结间膜的通道数不超过约25个/mum 2。跳跃传导和脱髓鞘疾病的这些发现的意义进行了讨论。
The density of sodium channels in mammalian myelinated fibers has been estimated from measurements of the binding of [3H]saxitoxin to rabbit sciatic nerve. Binding both to intact and to homogenized nerve consists of a linear, nonspecific, component and a saturable component that represents binding to the sodium channel. The maximum saturable binding capacity in intact nerve is 19.9 +/- 1.9 fmol-mg wet-1; the equilibrium dissociation constant, Kt, is 3.4 +/- 2.0 nM. Homogenization makes little difference, the maximum binding capacity being 19.9 +/- 1.5 fmol-mg wet-1 with Kt = 1.3 +/- 0.7 nM. These values correspond to a density of about 700,000 sodium channels per node--i.e., about 12,000 per mum2 of nodal membrane. From the difference between the values of maximum saturable binding capacity in intact and homogenized preparation, given the statistical uncertainty of their estimate, it seems that the internodal membrane can have no more than about 25 channels per mum2. The significance of these findings for saltatory conduction and in demyelinating disease is discussed.