Nerve Conduction Velocity through the Ventral Root Afferent Fibers in the Cat

고양이 척수전근 감각신경섬유의 흥분전도속도

  • Kim, Jun (Department of Physiology, College of Medicine, Seoul National University) ;
  • Hwang, Sang-Ik (Department of Physiology, College of Medicine, Seoul National University) ;
  • Ho, Won-Kyung (Department of Physiology, College of Medicine, Chungbuk National University)
  • 김전 (서울대학교 의과대학 생리학교실) ;
  • 황상익 (서울대학교 의과대학 생리학교실) ;
  • 호원경 (충북대학교 의과대학 생리학교실)
  • Published : 1987.06.30

Abstract

This study was aimed to investigate whether the conduction velocity of nerve impulses through the ventral afferent fibers is constant along their entire courses in dorsal as well as in ventral roots. Cats were anesthetized with ${\alpha}-chloralose$ (60 mg/kg, i.p.) and artificially ventilated. Laminectomies were done on L4-S1 spinal vertebrae to expose the lumbosacral spiral cord. Both ventral and dorsal roots of L7 or S1 spinal segments were isolated and cut near the spinal cord. Ventral roots were placed on 6-lead stimulating electrodes and stimulated with supra C-threshold intensity. Divided dorsal root fascicles were placed on bipolar recording electrodes and single fiber units activated by the stimulation of the ventral roots were identified. Followings are the results obtained: 1) A total of 27 VRA units were identified. 10 units of them conducted impulses slower than 2 m/sec. Conduction velocities of the remaining units were in the range of 3.11-20.91 m/sec. 2) In 12 Units conduction velocities Of the VRA units through dorsal$(CV_{DR})$ and venral root$(CV_{DR})$ were determined respectively. There was a tendency to conduct impulses faster through dorsal roots$(CV_{DR}=8.19{\pm}3.26\;m/sec)$ than ventral roots$(CV_{DR}=3.46{\pm}1.02\;m/sec)$. From the above results we confirmed that there exist nerve fibers in continuity between the spinal ventral and dorsal roots but we could not ascertain whether there is a change in conduction velocity through the entire course of ventral afferent unit.

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