Decherchi P, Darques J L, Jammes Y
Laboratoire de Physiopathologie Respiratoire Intégrée et Cellulaire (EA 2201), Institut Jean Roche, Faculté de Médecine, Université de la Méditerranée, Marseille, France.
J Peripher Nerv Syst. 1998;3(4):267-76.
Although previous experiments with a partially similar objective have been described in dogs, cats and rabbits, the purpose of this study was to identify and characterize mechanosensitive and chemosensitive muscle afferents in the anaesthetized rat since it is a widely used laboratory animal. The peroneal nerve innervating the tibialis anterior muscle was studied. Measurement of conduction velocities from compound action nerve potentials evoked by peripheral nerve stimulation allowed identification of group I-II (10.79+/-1.02 m/s), group III (2.96+/-0.58 m/s) and group IV (0.46+/-0.07 m/s) afferent fibers. Computation of the different compound potential areas showed that afferents I and II arising from spindles and tendon organs represented 9.65+/-2.2%, whereas afferents III and IV arising from free nerve endings in muscle represented 90.35+/-2.2% (III, 46.66+/-2.71% and IV, 43.69+/-2.52%). Action potentials were recorded from teased nerve filaments. Mechanical tendon vibrations (10 to 90 Hz) were used to activate mechanoreceptors. Peak increase in afferent discharge (fimpulses) was measured at 50 Hz (n = 12/19 units) or 70 Hz (n = 7/19 units). Intra-arterial bolus injections of different concentrations of potassium chloride (KCl: 1 to 20 mM) or lactic acid (LA: 0.5 to 3 mM) elicited marked activation of III and IV afferents (n = 124). Enhancement of fimpulses was not proportional to the increase in [KCl] or [LA]. Activation of afferents plateaued when [KCl] was equal or greater than 5 mM while fimpulses peaked, then decreased, when [LA] was 1 mM. Muscle fatigue induced by direct electrical muscle stimulation (EIF) markedly activated group III-IV (n = 17/18) afferents (176.9+/-29.7% of control) which persisted for the 3 minutes of recovery from fatigue. Maximal fimpulses increases in response to LA (+67%) and KCl (+46.9%) injections and to EIF (+76.9%) were similar. This procedure for characterizing the functional properties of sensory nerve endings in a skeletal muscle may be used to assess further changes in sensory muscle paths in experimental rodent pathophysiological systems.
尽管之前在犬、猫和兔身上进行过部分目标相似的实验，但本研究的目的是鉴定和描述麻醉大鼠体内的机械敏感和化学敏感肌肉传入神经，因为大鼠是一种广泛使用的实验动物。研究了支配胫骨前肌的腓总神经。通过测量外周神经刺激诱发的复合动作电位的传导速度，可识别出I-II组（10.79±1.02 m/s）、III组（2.96±0.58 m/s）和IV组（0.46±0.07 m/s）传入纤维。对不同复合电位面积的计算表明，来自肌梭和腱器官的I和II类传入神经占9.65±2.2%，而来自肌肉中游离神经末梢的III和IV类传入神经占90.35±2.2%（III组，46.66±2.71%；IV组，43.69±2.52%）。从分离的神经细丝记录动作电位。使用机械性肌腱振动（10至90 Hz）来激活机械感受器。在50 Hz（n = 12/19个单位）或70 Hz（n = 7/19个单位）时测量传入放电（f冲动）的峰值增加。动脉内推注不同浓度的氯化钾（KCl：1至20 mM）或乳酸（LA：0.5至3 mM）可显著激活III和IV类传入神经（n = 124）。f冲动的增强与[KCl]或[LA]的增加不成比例。当[KCl]等于或大于5 mM时，传入神经的激活达到平台期，而当[LA]为1 mM时，f冲动达到峰值，然后下降。直接电刺激肌肉（EIF）诱导的肌肉疲劳显著激活III-IV组（n = 17/18）传入神经（为对照的176.9±29.7%），在从疲劳恢复的3分钟内持续存在。对LA（+67%）、KCl（+46.9%）注射以及EIF（+76.9%）反应的最大f冲动增加相似。这种用于表征骨骼肌感觉神经末梢功能特性的方法可用于评估实验性啮齿动物病理生理系统中感觉肌肉通路的进一步变化。
