ACTION-POTENTIALS AND MEMBRANE CURRENTS IN THE HUMAN NODE OF RANVIER
ACTION-POTENTIALS AND MEMBRANE CURRENTS IN THE HUMAN NODE OF RANVIER
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DOI：
10.1007/bf00374660
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发表时间：
1995-06-01
影响因子：
4.5
通讯作者：
BOSTOCK, H
中科院分区：
文献类型：
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作者：
SCHWARZ, JR;REID, G;BOSTOCK, H
在室温下的电流和电压钳条件下，记录了单个人有髓神经纤维的动作电位和膜电流。神经材料取自接受神经移植手术的患者。对11根神经纤维进行了成功的记录。在Ringer‘s液中，记录到大的瞬时钠电流，该电流可被河豚毒素完全阻断。用3 nM河豚毒素部分阻断这些电流，以减小串联电阻引起的电压钳位误差。外向钾电流在完整的神经纤维中很小，但在纤维中有很大的幅度，显示出结旁脱髓鞘的迹象。在等渗氯化钾中，钾电流可分为三个分量：两个快分量(K-f1和K-f2)和一个慢分量(K-S)。在-145 mV到+115 mV的电位范围内，测量了钠通透性和快钾电导和慢钾电导的稳态激活和失活时间常数。根据这些参数，计算了相应的速率常数，并根据Frankenhaeuser-Huxley方程建立了数学模型。计算的动作电位与记录的动作电位非常接近。去掉快K电导或慢K电导对单个计算的动作电位影响不大，但需要慢K电导来限制模型对长时间刺激电流的重复反应。
Action potentials and membrane currents were recorded in single human myelinated nerve fibres under current- and voltage-clamp conditions at room temperature. Nerve material was obtained from patients undergoing nerve graft operations. Successful recordings were made in 11 nerve fibres. In Ringer's solution, large transient Na currents were recorded, which could be blocked completely with tetrodotoxin. Partial block of these currents with 3 nM tetrodotoxin was used to reduce the voltage-clamp error due to series resistance. Outward K currents were very small in intact nerve fibres, but had a large amplitude in fibres showing signs of paranodal demyelination. In isotonic KCl, the K current could be separated into three components: two fast components (K-f1 and K-f2) and one slow component (K-s). Time constants and steady-state activation and inactivation of Na permeability and of fast and slow K conductance were measured within the potential range of -145 mV to +115 mV. From these parameters, the corresponding rate constants were calculated and a mathematical model based on the Frankenhaeuser-Huxley equations was derived. Calculated action potentials closely matched those recorded. Single calculated action potentials were little affected by removing the fast or slow K conductance, but the slow K conductance was required to limit the repetitive response of the model to prolonged stimulating currents.