Saltatory conduction of peripheral nerve impulse in clioquinol-treated rats

By using a new method, unidimensional latency-topography, which shows the saltatory conduction pattern of an impulse along peripheral nerve fibers, the internodal length, internodal conduction time and conduction velocity were determined from the L5 ventral and/or dorsal root filaments of clioquinol-treated rats (CTR). The saltatory conduction pattern was preserved in most of the CTR fibers tested, but was not seen in some fibers. A positive correlation was seen between the conduction velocity and the internodal length in the nerve fibers of both the normal rats and CTR. Although there was no difference in the internodal length between normal rats and CTR, conduction velocities determined in CTR fibers were lower than those in normal rat fibers. Myelin length was calculated from the saltatory conduction pattern in the topography to represent the functional length of the saltatory conduction. The functional myelin length of the CTR fiber was shorter than that of normal rats. Shortening of the functional myelin length in CTR is due to the widening of the Ranvier node, which corresponds to the exposure of the Ranvier node, i.e. demyelination. It was concluded that the decrease in conduction velocity in CTR fibers was due to exposure which caused delayed excitation at the Ranvier nodes.