Lumbar sympathetic ganglia in man: an electrophysiological study in vitro

A method has been developed for the removal, preservation and electrophysiological study 'in vitro' of sympathetic lumbar chains (L1-L3) from subjects undergoing lumbar ganglionectomy in the treatment of peripheral vascular diseases. Extracellular recordings from interganglionic trunks, and intracellular recordings from single sympathetic neurons, were performed. The extracellular experiments substantiated the concept, hitherto deduced from animal experiments, that the preganglionic fibres in the sympathetic lumbar chain are mainly of a descending nature. In fact, stimulation of the interganglionic trunk cranial to ganglia is always much more effective in driving ganglion neurons to fire than stimulation of the interganglionic trunk caudal to ganglia. The intracellular experiments produced a good definition of the main electrical characteristics of human sympathetic neurons. The results can be summarized as follows: the resting membrane potential ranged from 50 to 75 mV (63.4 +/- 9.2 mV; 21 neurons); action potential amplitude from 62 to 93 mV (74.3 +/- 8.1 mV; 27 neurons); membrane input resistance was 42.3 +/- 12.6 m omega (8 neurons) and total membrane capacitance 83.7 +/- 15.3 pF (8 neurons).