Kunimoto M, Kirnö K, Elam M, Karlsson T, Wallin B G
Department of Clinical Neurophysiology, Sahlgren's Hospital, University of Göteborg, Sweden.
Acta Physiol Scand. 1992 Nov;146(3):385-92. doi: 10.1111/j.1748-1716.1992.tb09433.x.
Intraneural electrical stimuli (0.3 mA, 0.2 ms) were delivered via a tungsten microelectrode inserted into a cutaneous fascicle in the median nerve at the wrist in 16 normal subjects, and the effects on the sweat glands within the innervation zone were recorded as changes of skin resistance. In order to examine the relationship between the skin resistance level and the amplitude of transient resistance responses, trains of high frequency stimulation were used to reduce the skin resistance level and then transient resistance responses were evoked by single stimuli at 0.1 Hz. Regional anaesthesia of the brachial plexus in the axilla eliminated spontaneous sympathetic activity and reflex effects. At high skin resistance levels response amplitudes to single stimuli were low but they increased successively to a maximum at intermediate levels and then decreased again at low resistance levels. Repeated stimulation sequences evoked qualitatively similar response curves but quantitatively both response amplitudes and skin resistance levels were slightly reduced upon repetition. We suggest that the changes of response amplitudes are due to variable resistivity of the corneal layer. The shifts of the response curves with repetition of stimulation may result from increased hydration of the corneum. It is concluded that the variability of response amplitudes to constant stimuli makes the amplitude of a skin resistance response unsuitable as an indicator of the strength of sympathetic sudomotor nerve traffic.
对16名正常受试者，通过插入腕部正中神经皮束的钨微电极施加神经内电刺激（0.3毫安，0.2毫秒），并将对神经支配区内汗腺的影响记录为皮肤电阻的变化。为了研究皮肤电阻水平与瞬态电阻反应幅度之间的关系，使用高频刺激序列降低皮肤电阻水平，然后以0.1赫兹的单刺激诱发瞬态电阻反应。腋窝臂丛神经区域麻醉消除了自发交感神经活动和反射效应。在高皮肤电阻水平下，对单刺激的反应幅度较低，但在中等水平时依次增加至最大值，然后在低电阻水平时再次降低。重复刺激序列诱发了定性相似的反应曲线，但重复时反应幅度和皮肤电阻水平在数量上均略有降低。我们认为反应幅度的变化是由于角质层电阻率可变所致。刺激重复时反应曲线的偏移可能是由于角质层水合作用增加。结论是，对恒定刺激的反应幅度变化使得皮肤电阻反应幅度不适宜作为交感神经汗腺运动神经活动强度的指标。
