Conducting pathways of sympathetic ganglia of the cat solar plexus

Abstract

1. Data on responses in nerves of the solar plexus to stimulation of its other nerves, their amplitude, latency, threshold, and the influence of diplacin, blocking synaptic transmission, and of the frequency of stimulation are used to deduce a scheme for the conducting pathways through ganglia of the solar plexus. 2. The splanchnic nerves contain fibers with a conduction velocity of 20.0±0.9 m/sec, which pass through the ganglia into nerves of the celiac and mesenteric plexuses without interruption (these are presumably afferent fibers). 3. The mean conduction velocity of the preganglionic fibers of the splanchnic nerve is 3.3±0.17 m/sec. These fibers terminate synaptically in the ganglia; synaptic delay in this transmission averages 5.2±0.45 msec, and its mediator is acetylcholine. 4. The conduction velocity in the postganglionic fibers of peripheral nerves of the solar plexus is 0.8±0.03 m/sec. 5. Connections between the peripheral nerves of ganglia of the solar plexus are found through these ganglia, with participation of synapses. Pathways of true peripheral reflexes evidently pass through here, and the mediator in the synapses is also acetylcholine. 6. A conducting pathway passes from one nerve of the celiac plexus into the left greater splanchnic nerve, interrupted synaptically in the ganglia of the solar plexus. The mediator of this transmission is not acetylcholine.