抄録
Many clinical studies have indicated the usefulness of Neurometer in the quantification of nerve dysfunction in patients. It is reported that the three sine-wave pulses at 2000-, 250-, and 5-Hz produced by the device selectively stimulate Aβ-, Aδ- and C afferent fibers, respectively. However, there are few electrophysiological studies showing the selectivity. Intracellular recordings were made from dorsal root ganglion (DRG) neurons and action potentials (APs) elicited by the sine-wave pulse were analyzed. L4-6 DRGs were isolated from 7-8-week-old rats together with a proximal dorsal root having a length of 7-12 mm. Antidromic stimulation at the central end of the dorsal root was performed with a suction electrode to classify recorded neurons into one of three groups, Aβ-, Aδ-and C-type, on the basis of a combination of values of the axonal conduction velocity, duration of AP and threshold stimulus intensity. After the identification of cell type, the dorsal root was stimulated with Neurometer. Aβ-fibers recorded were activated by all the three sine-wave stimuli. Ad-fibers were excited by 250-Hz and 5-Hz stimuli. The frequencies of APs elicited in these A fibers were higher at 250-Hz than other stimuli. On the other hand, C-fibers were only activated by 5-Hz stimuli. These results indicate that Neurometer makes possible to examine the selective activation of the peripheral nerves that differ in diameter. The present study in DRG may provide a basic knowledge for evaluating an effect of analgesic drugs and a change in pain sensation in human. [Jpn J Physiol 54 Suppl:S171 (2004)]
