An electrophysiological study on the mechanoreceptors in the lumbar intervertebral disc and the posterior longitudinal ligament.

实验用成年猫12只，体重2.3-5.6公斤(平均3.1公斤)。静脉注射戊巴比妥钠维持麻醉。和潘克罗溴铵静脉注射，使用人工呼吸机。L1~L7椎板切除。然后分离L5-L7背根，在其近端切断。然后将每个小根覆盖在一个双极电极上。为研究机械敏感传入单位在PLL内的感受野，用玻璃探头记录机械刺激对PLL的传入冲动。当感受野被识别后，用双极电极电刺激它们获得传导速度(CVs)，并用一组17根尼龙丝刺激它们来确定机械阈值。在这12个单位中，9个位于椎体部分，其余位于…在椎间盘部分有更多的肿块。这些单位的机械阈值为20.90-67.80克(平均45.40克)。所有这些单元都具有较高的机械阈值(大于7.0g)。仅1个单位的CV值为0.5~2.5m/s(IV组)，其余11个单位的CV值为2.5~20m/s(III组)。感觉神经纤维按其直径和CV值分为I~IV组。机械阈值高(大于7.0g)的机械敏感单位被认为是伤害性感受单位。另一方面，被归类为第二类或第三类且阈值较低(低于7.0g)的那些被认为是本体感觉单位。本研究中确定的所有单位都有一个高阈值，并被归类为组III或IV。如上所述，本研究中确定的所有单位都被认为是伤害性单位。这一结果表明，来自腰椎PLL的传入纤维主要参与注意功能，而不是本体感觉功能。尽管腰椎PLL可能参与了由于对不稳定或应激的反应而导致的下腰痛的机制。较少

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