title: Intestinal peristalsis associated with release of immunoreactive substance P.
abstract: The release of immunoreactive substance P into the vascular bed of the isolated small intestine of the guinea-pig was investigated. Raising the intraluminal pressure to 5 mbar for 5 min initiated peristalsis and stimulated the release of substance P. The substance P releasing effect of pressure stimulation was reduced by 46% when hexamethonium (240 microM) was added to the perfusion solution. The ganglion stimulant drug dimethylphenylpiperazinium (32 microM) also stimulated the release of substance P; its effect was completely prevented by hexamethonium (240 microM). Intraarterial infusion of capsaicin (22 microM), a neurotoxin known to act on sensory substance P-containing neurones, stimulated the release of substance P and caused intestinal contractions. The motor effect of capsaicin in the gut can thus be explained by release of substance P from sensory nerve endings in the gut. Systemic pretreatment of the guinea-pigs with capsaicin abolished the release of substance P due to capsaicin, whereas that evoked by elevated intraluminal pressure or dimethylphenylpiperazinium was not reduced. This means that substance P released in the course of peristalsis or by dimethylphenylpiperazinium originates from neurones intrinsic to the intestine. These findings indicate that intestinal peristalsis is associated with the release of substance P from enteric neurones. Substance P is likely to be a neurotransmitter involved in the coordination of the peristaltic reflex.
mesh_terms: D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D005260:Female; D005769:Gastrointestinal Motility; D006168:Guinea Pigs; D007422:Intestines / Q000098:blood supply; D008297:Male; D018377:Neurotransmitter Agents / Q000502:physiology; D011188:Potassium / Q000494:pharmacology; D012018:Reflex / Q000502:physiology*; D013373:Substance P / Q000097:blood / Q000502:physiology*; D009435:Synaptic Transmission
chemical_list: D018377:Neurotransmitter Agents; D013373:Substance P; D004246:Dimethylphenylpiperazinium Iodide; D011188:Potassium; D002211:Capsaicin