Overcoming conduction failure in demyelinated nerve fibres by prolonging action potentials

摘要: LOSS of myelin from central or peripheral myelinated nerve fibres results in conduction delays, increased refractoriness and, above all, block1,2. Conduction failure could result either because a demyelinated axon is electrically inexcitable, the limited current available normal node insufficient to excite it. Because continuous along internodes has been observed3, it seems likely that axons general are able conduct impulses, but impedance mismatch at junction and usually prevents realisation this ability. In support this, two factors have shown improve transmission experimental demyelination also, transiently, multiple sclerosis patients: lowered calcium ion concentration4,5, which reduces threshold for excitation, temperature6,7, prolongs action potential thereby increases time integral depolarise axon. To test suggestion drug specifically might prove useful therapy demyelinating diseases8, we compared effects temperature scorpion venom on single through lesion rat spinal roots.