[Natural electrical activity of human sympathetic nerve fibers recorded from the body surface]

The electrical potentials recorded from human forearm were stored and averaged as synchronous with the cardiac rhythm. The R-wave of the ECG was used to synchronize the averaging system. The record obtained with this technique from human forearm during transient stop of blood flow to avoid mechanical artifacts was a sinusoid-like curve with peaks between the R-waves of the ECG. The nature of this electronegative wave was investigated by means of comparing electrograms and rheograms recorded from forearm of normal subjects and subjects after denervation or desympathization of their upper extremities. The data obtained suggest that the electronegative wave recorded with this technique is the averaged sum of tonic pulse-synchronous electrical activity of sympathetic nerve's fibers innervating vasoconstrictors of the skeletal muscle.