Properties of synaptic inputs from myenteric neurons innervating submucosal S neurons in guinea pig ileum.
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.
Moore
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BA
Gastrointestinal Diseases Research Unit, Departments of Medicine, Physiology, and Biology, Queen's University, Kingston, Ontario, Canada K7L 5G2.
Vanner
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S
D000818:Animals; D004558:Electric Stimulation; D004566:Electrodes; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005260:Female; D006168:Guinea Pigs; D018738:Hexamethonium / Q000494:pharmacology; D007082:Ileum / Q000294:innervation*; D007211:Indoles / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000294:innervation*; D008297:Male; D009197:Myenteric Plexus / Q000166:cytology*; D009474:Neurons / Q000502:physiology*; D013498:Suramin / Q000494:pharmacology; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology; D000077526:Tropisetron
D007211:Indoles; D018738:Hexamethonium; D013779:Tetrodotoxin; D013498:Suramin; D000077526:Tropisetron