OVERCOMING CONDUCTION FAILURE IN DEMYELINATED NERVE-FIBERS BY PROLONGING ACTION POTENTIALS
OVERCOMING CONDUCTION FAILURE IN DEMYELINATED NERVE-FIBERS BY PROLONGING ACTION POTENTIALS
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DOI：
10.1038/274385a0
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发表时间：
1978-01-01
期刊：
影响因子：
64.8
通讯作者：
SEARS, TA
中科院分区：
文献类型：
--
作者：
BOSTOCK, H;SHERRATT, RM;SEARS, TA
中枢或外周有髓神经纤维髓鞘丢失导致传导延迟、不应性增加，尤其是传导阻滞1，2。由于脱髓鞘的轴突不能电兴奋，或者正常节点提供的有限电流不足以兴奋它，导致传导失败。由于脱髓鞘的节间沿着连续传导已被破坏3，脱髓鞘的轴突一般似乎能够传导冲动，但是正常和脱髓鞘轴突连接处的阻抗失配通常阻止这种能力的实现。为了支持这一点，两个因素已被证明可以改善实验性脱髓鞘和多发性硬化症患者的传输：降低钙离子浓度4，5，这降低了神经兴奋的阈值，降低了温度6，7，这降低了动作电位，从而增加了去极化和兴奋脱髓鞘轴突的电流的时间积分。为了验证一种能特异性抑制动作电位的药物在脱髓鞘疾病的治疗中可能有用的建议，我们比较了温度和蝎毒对大鼠脊神经根脱髓鞘病变中单纤维传输的影响。
LOSS of myelin from central or peripheral myelinated nerve fibres results in conduction delays, increased refractoriness and, above all, conduction block1,2. Conduction failure could result either because a demyelinated axon is electrically inexcitable, or because the limited current available from a normal node is insufficient to excite it. Because continuous conduction along demyelinated internodes has been observed3, it seems likely that demyelinated axons in general are able to conduct impulses, but that the impedance mismatch at the junction of normal and demyelinated axon usually prevents the realisation of this ability. In support of this, two factors have been shown to improve transmission in experimental demyelination and also, transiently, in multiple sclerosis patients: lowered calcium ion concentration4,5, which reduces the threshold for nerve excitation, and lowered temperature6,7, which prolongs the action potential and thereby increases the time integral of current available to depolarise and excite the demyelinated axon. To test the suggestion that a drug that specifically prolongs the action potential might prove useful in the therapy of demyelinating diseases8, we have compared the effects of temperature and a scorpion venom on transmission in single fibres through a demyelinating lesion in rat spinal roots.