Tonic sympathetic activity in the sciatic nerve of the rabbit

Spontaneous sympathetic activity of tibial and peroneal nerves was investigated in anaesthetized rabbits using the multichannel coherent recording technique. The tonic activity of these fibres is shown to be mainly irregular. Sometimes it correlates with the cardiac rhythm. No modulation with 10 c/s frequency described by other researchers and no respiratory modulation are observed. At constant arterial pressure the amplitude of irregular changes in the nerve activity exceeded several times the average level of the activity.