Properties of synaptic inputs from myenteric neurons innervating submucosal S neurons in guinea pig ileum

• Published in: American journal of physiology: Gastrointestinal and liver physiology Vol. 278; no. 2; p. G273
• Main Authors: Moore, B A, Vanner, S
• Format: Journal Article
• Language: English
• Published: United States 01-02-2000
• Subjects: Animals; Electric Stimulation; Electrodes; Excitatory Postsynaptic Potentials - physiology; Female; Guinea Pigs; Hexamethonium - pharmacology; Ileum - innervation; Indoles - pharmacology; Intestinal Mucosa - innervation; Male; Myenteric Plexus - cytology; Neurons - physiology; Suramin - pharmacology; Synapses - physiology; Synaptic Transmission - drug effects; Synaptic Transmission - physiology; Tetrodotoxin - pharmacology
• ISSN: 0193-1857
• DOI: 10.1152/ajpgi.2000.278.2.g273

This study examined synaptic inputs from myenteric neurons innervating submucosal neurons. Intracellular recordings were obtained from submucosal S neurons in guinea pig ileal preparations in vitro, and synaptic inputs were recorded in response to electrical stimulation of exposed myenteric plexus. Most S neurons received synaptic inputs [>80% fast (f) excitatory postsynaptic potentials (EPSP), >30% slow (s) EPSPs] from the myenteric plexus. Synaptic potentials were recorded significant distances aboral (fEPSPs, 25 mm; sEPSPs, 10 mm) but not oral to the stimulating site. When preparations were studied in a double-chamber bath that chemically isolated the stimulating "myenteric chamber" from the recording side "submucosal chamber," all fEPSPs were blocked by hexamethonium in the submucosal chamber, but not by a combination of nicotinic, purinergic, and 5-hydroxytryptamine-3 receptor antagonists in the myenteric chamber. In 15% of cells, a stimulus train elicited prolonged bursts of fEPSPs (>30 s duration) that were blocked by hexamethonium. These findings suggest that most submucosal S neurons receive synaptic inputs from predominantly anally projecting myenteric neurons. These inputs are poised to coordinate intestinal motility and secretion.