Spinal sympathetic conduction velocity in humans.

Simultaneous micro-electrode recordings of muscle sympathetic activity were made in the radial nerve at the mid-humerus level and the peroneal nerve at the fibular head in 8 healthy subjects. Sympathetic impulses occurred spontaneously in multi-unit bursts time-locked to the cardiac rhythm. There was a high degree of similarity between radial and peroneal neurograms with the radial bursts preceding corresponding peroneal ones by approximately 0.35 s. Utilizing this latency difference and previously determined values for peripheral sympathetic postganglionic conduction velocities, we calculated that the spinal conduction velocity for muscle sympathetic activity is 2.8 +/- 0.7 m/s (mean +/- SD). The result agrees with similar data from experimental animals.