Myoelectric properties of the cat ileocecal sphincter

Ann Ouyang, W. J. Snape, S. Cohen

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Myoelectric activity and intraluminal pressures were recorded simultaneously from the ileum, ileocecal sphincter (ICS), and proximal colon in chloralose-anesthetized cats. Slow-wave activity, seen at all areas, showed coupling of frequency in the distal ileum and ICS. ICS spike activity was both isolated and associated with ileal or colonic spike activity and correlated with phasic contractions (r = 0.86; P <0.01). Ileal distensions caused ICS relaxation and decreased spike activity 33.8% of the time. Colonic distensions caused contraction and increased spike activity 46.9% of the time. Migrating action-potential complexes (MAPC) induced by castor oil, ricinoleic acid, or cholecystokinin propagated to the ICS and through to the colon significantly more frequently than ileal non-MAPC (P <0.05). Both spike potential-dependent and spike potential-independent mechanisms were involved in ICS contraction. Bethanechol increased spike activity and phasic and tonic contractions. Phenylephrine, despite loss of spike activity in all leads, caused tonic contraction of the ICS. Isoproterenol caused loss of spike activity and decreased ICS pressure. Thus, ICS myoelectric activity appears to be important in determining sphincter function during neurohumoral and mechanical stimulation, with ICS contractions occurring through both a phasic spike-related mechanism and a tonic mechanism without spike activity.

Original languageEnglish (US)
Pages (from-to)G450-G458
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume3
Issue number6
DOIs
StatePublished - 1981

All Science Journal Classification (ASJC) codes

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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