Activation of postganglionic neurones via non-nicotinic synaptic mechanisms by stimulation of thin preganglionic axons.

Activity in postganglionic neurones supplying skeletal muscle and hairy skin of the cat hindlimb was measured after single and repetitive stimulation of preganglionic axons in the lumbar sympathetic trunk at variable stimulation strengths. Simultaneously the compound action potentials were measured in one of the lumbar white rami L2 or L3. Early short latency ("nicotinic") responses were obtained in the postganglionic neurones when preganglionic axons conducting at 8.9 +/- 3.44 m/s (n = 12) or less were stimulated. Late, long-latency non-nicotinic responses were elicited in the postganglionic neurones when preganglionic axons conducting at 1.52 +/- 0.94 m/s (n = 12) or less were stimulated.