In recent years it has become possible to measure a number of activities of the autonomic nervous system in man, and in abnormal man attempts are made to localize the site of the lesion. When an abnormality of sympathetic activity has been shown to be due to a lesion in the efferent pathway, it is desirable to show whether the lesion is in the postganglionic fibre or more proximal. Existing tests based on the effect of injected acetylcholine have proved difficult to interpret. The present communication describes observations on the electrophoresis of acetylcholine and its effect on local sweating in normal and abnormal man. It presents evidence that electrophoresis of acetylcholine provides a reliable means of examining the function of postganglionic nerves supplying sweat glands. It is simple to perform and interpret, semi-quantitative, objective, and can localize the skin areas involved.
METHODS AND MATERIALELECTROPHORESIS Acetylcholine was applied to the sweat glands by electrophoresis. The anode was a silver electroencephalography electrode enclosed in lint to give an area of 1 cm2 in contact with the skin. The cathode was much larger, a sheet of malleable metal wrapped in lint. The current, provided by three nine-volt batteries connected in series, was regulated with a 100,OOOQ variable resistance and measured on a 2mA meter. The anode was moistened with a freshly prepared 1 % solution of acetylcholine perchlorate, the cathode with tap water. To apply the drug a current of 0i125, 0-25, 0 50, 10, or 2-0 mA was passed between the electrodes for a timed period of 0-25, 0 50, 1 0, or 2-0 minutes.Thermal sweating The subject's central temperature was raised either in a hot bath (40°to 44'C), or with a radiant heat cradle over the trunk or by placing one forearm and hand in a stirred waterbath at 400 to 44°C. This was continued until there was profuse generalized sweating or the oral temperature had risen 1 'C.