Peripheral sympathetic pathways to gastroduodenal region of the guinea pig.

The sympathetic pathways to the stomach and duodenum of the guinea pig were studied by electrical nerve stimulation and by gastric distension in vitro and in vivo. The in vitro preparation consisted of the stomach and duodenum connected by para-arterial nerves to the celiac plexus. Gastroduodenal motility was measured with intraluminal pressure catheters. Stimulation of splanchnic nerves resulted in inhibition of propulsive contractions of both the stomach and duodenum. Stimulation of the left gastric nerve inhibited the stomach but not the duodenum, and stimulation of the gastroduodenal nerve inhibited the duodenum only. When the gastroduodenal nerve was stimulated, excitatory postsynaptic potentials were elicited in 18% of the cells from which intracellular recordings were made in the celiac ganglia. When the stomach was distended to a pressure of 5-7 cmH2O, propulsive contractions in the duodenum stopped in 86% of the distensions in the in vivo preparations and in 62% of the distensions in the in vitro preparations. Section of the gastroduodenal nerve eliminated the distension-induced inhibition of duodenal propulsion in vitro. These experiments describe the efferent sympathetic pathways to the celiac plexus of the guinea pig and demonstrate reflex pathways to the celiac plexus that can mediate a gastroduodenal inhibitory reflex.