Smith A M, Cadoret G, St-Amour D
Centre de Recherche en Sciences Neurologiques, Département de Physiologie, Université de Montréal, Quebec, Canada.
Exp Brain Res. 1997 May;114(3):578-83. doi: 10.1007/pl00005666.
The aim of this study was to determine whether relatively long-term changes in skin friction induced by a pharmacological blockade of sweat excretion would alter the grip forces applied to objects of a variety of different surface textures and frictions. Five men and three women were asked to lift the vertically mounted armature of a linear motor between the thumb and index finger and to hold it against an opposing force for 2 s. A 1.0-kHz tone indicated to the subject that the manipulandum had been correctly positioned between the upper and lower position limits. The linear motor generated a 2.5-N force tangential to the skin surface simulating an object weighing approximately 250 g. Three different polyamide plastic surfaces (either smooth or etched with 1.0 mm high Braille beads evenly spaced at 2- or 3-mm intervals) contacted the fingers in these experiments. Subjects lifted and held in a precision grip one of the three surfaces for blocks of ten consecutive trials, but the order of presentation of the three different textures was varied to offset the effect of expectancy. On a second block of ten trials the subjects were requested to release the object slowly to measure the ratio of the grip force normal to the grasped surface to the tangential load force at the moment of slip. This ratio or its inverse provided the coefficient of friction or the slip ratio for a particular subject and surface condition. Twelve hours prior to a second recording session all subjects placed transdermal patches of 1.5 mg scopolamine behind each ear to reduce palmar sweating by blocking the muscarinic receptors of exocrine sweat glands. The subjects were re-tested following procedures that were identical to the first session. Scopolamine significantly reduced the friction of the skin on the smooth and 2-mm beaded surfaces, but the friction of the 3-mm beaded texture was unaffected. Scopolamine also caused subjects to increase both the peak and static grip forces for all the textures including the 3-mm beaded surface, suggesting that for two of the three surfaces they were responding to the increased slipperiness of the skin due to reduced sweat production.
本研究的目的是确定通过药物阻断汗液分泌所引起的皮肤摩擦力的相对长期变化是否会改变施加于各种不同表面纹理和摩擦力物体上的握力。五名男性和三名女性被要求用拇指和食指提起线性电机垂直安装的衔铁，并将其抵住相反的力保持2秒。1.0千赫的音调向受试者表明操作器已正确定位在上、下位置极限之间。线性电机产生一个与皮肤表面相切的2.5牛的力，模拟一个重约250克的物体。在这些实验中，三种不同的聚酰胺塑料表面（光滑的或蚀刻有间隔2毫米或3毫米均匀分布的1.0毫米高盲文珠子）与手指接触。受试者以精确握法提起并握住三种表面之一，连续进行十次试验，但三种不同纹理的呈现顺序有所变化，以抵消预期效应。在第二个十次试验组中，要求受试者缓慢释放物体，以测量在滑动瞬间垂直于被抓握表面的握力与切向负载力的比值。这个比值或其倒数提供了特定受试者和表面条件下的摩擦系数或滑动率。在第二次记录 session 前12小时，所有受试者在每只耳朵后面贴上1.5毫克东莨菪碱的透皮贴片，通过阻断外分泌汗腺的毒蕈碱受体来减少手掌出汗。受试者按照与第一次 session 相同的程序重新进行测试。东莨菪碱显著降低了皮肤在光滑表面和间隔2毫米珠子表面的摩擦力，但间隔3毫米珠子纹理的摩擦力未受影响。东莨菪碱还使受试者对所有纹理（包括间隔3毫米珠子表面）的峰值和静态握力都有所增加，这表明对于三种表面中的两种，他们是在对由于汗液分泌减少导致的皮肤增加的滑爽性做出反应。
