| Project/Area Number |
09671507
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Orthopaedic surgery
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| Research Institution | Sapporo Medical University |
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Principal Investigator |
YAMASHITA Toshihiko Sapporo Medical University, Assistant Prof.., 医学部, 助教授 (70244366)
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| Co-Investigator(Kenkyū-buntansha) |
YOKOGUSHI Kazutoshi Sapporo Medical University, Assistant Prof.., 医学部, 助教授 (20145593)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1999: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1997: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | mechanoreceptor / nociceptor / posterior longitudinal ligament / sacroiliac joint / low-back pain / electrophysiology / 腰椎 / 後縦靱帯 / 電気生理学 / 固有感覚受容器 |
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| Research Abstract |
The experiments were carried out using twelve adult cats weighing 2.3-5.6 kg (avr., 3.1 kg). The anesthesia was maintained by sodium pentobarbital i.v. And pancronium bromide i.v., using an artificial ventilation machine. Laminectomy was performed on L1 to L7. Then the L5-L7 dorsal rootlets were separated and cut at their proximal ends. Each rootlet was then draped over a bipolar electrode. To investigate the receptive fields of the mechanosensitive afferent units in the PLL, afferent impulses that were evoked by the mechanical stimulation on the PLL with a glass probe were recorded. When the receptive fields were identified, they were stimulated electrically with a bipolar electrode to obtain conduction velocities (CVs) and were stimulated with a set of seventeen nylon filaments to determine the mechanical thresholds.
Twelve mechanosensitive afferent units were identified in the lumbar PLL. Of these twelve units, nine were located in the vertebral body portion and the others were locat
… More
ed in the intervertebral disc portion. The mechanical thresholds of these units were 20.90-67.80 g (avr., 45.40 g). All of these units had high mechanical threshold (more than 7.0 g). Only one unit had a CV of 0.5-2.5 m/sec (group IV) and the remaining 11 units had CVs of 2.5-20 m/sec (group III).
Sensory nerve fibers were classified into groups I to IV according to their diameter and CV. Mechanosensitive units classified as group III or IV and with a high mechanical threshold (more than 7.0 g) have been thought to act as nociceptive units. On the other hand those classified as group II or III and with a low threshold (less than 7.0 g) have been thought to act as proprioceptive units. All of the units identified in this study had a high threshold and were classified as group III or IV. As mentioned above, all of the units identified in this study were thought to be nociceptive units. This result suggests that afferent fibers from the lumbar PLL principally contribute to the noticeptive function, not to the proprioceptive function. It is though that the lumbar PLL may be involved in the mechanisms of low back pain as a result of the reaction to instability or stress. Less
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