In vivo signal-transduction pathways to stimulate phasic contractions in normal and inflamed ileum

Sushil K. Sarna

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

We investigated the in vivo signal-transduction pathways to stimulate phasic contractions in normal and inflamed ileum by close intra-arterial infusions of test substances. Methacholine stimulated phasic contractions dose dependently. This response was suppressed during inflammation. Verapamil inhibited the response to methacholine dose dependently in both normal and inflamed ileum. Neomycin inhibited the response partially in normal ileum and almost completely in inflamed ileum. H-7 and chelerythrine partially inhibited the methacholine response in normal ileum but had no significant effect in inflamed ileum. Ryanodine stimulated phasic contractions that were blocked by TTX, hexamethonium, atropine, or ruthenium red. Ruthenium red, however, had no significant effect on the contractile response to methacholine. Conclusions: 1) Ca2+ influx through the L-type channels may be the primary source of Ca2+ to stimulate in vivo phasic contractions. 2) Phosphatidylinositol hydrolysis enhances the stimulation of in vivo phasic contractions in the normal ileum. In the inflamed ileum, phosphatidylinositol hydrolysis may be essential to stimulate phasic contractions. 3) Inflammation may downregulate the protein kinase C pathway. 4) Ryanodine stimulates phasic contractions by the release of ACh.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume274
Issue number4 37-4
StatePublished - Apr 1998
Externally publishedYes

Fingerprint

Ileum
Signal Transduction
Methacholine Chloride
Ruthenium Red
Ryanodine
Phosphatidylinositols
Hydrolysis
Inflammation
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine
Intra Arterial Infusions
Hexamethonium
Neomycin
Verapamil
Atropine
Protein Kinase C
Down-Regulation

Keywords

  • Calcium
  • Chelerythrine
  • Gastrointestinal motility
  • H-7
  • Inflammation
  • Neomycin
  • Protein kinase C
  • Ruthenium red
  • Ryanodine
  • Smooth muscle
  • W-7

ASJC Scopus subject areas

  • Gastroenterology
  • Physiology
  • Physiology (medical)

Cite this

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title = "In vivo signal-transduction pathways to stimulate phasic contractions in normal and inflamed ileum",
abstract = "We investigated the in vivo signal-transduction pathways to stimulate phasic contractions in normal and inflamed ileum by close intra-arterial infusions of test substances. Methacholine stimulated phasic contractions dose dependently. This response was suppressed during inflammation. Verapamil inhibited the response to methacholine dose dependently in both normal and inflamed ileum. Neomycin inhibited the response partially in normal ileum and almost completely in inflamed ileum. H-7 and chelerythrine partially inhibited the methacholine response in normal ileum but had no significant effect in inflamed ileum. Ryanodine stimulated phasic contractions that were blocked by TTX, hexamethonium, atropine, or ruthenium red. Ruthenium red, however, had no significant effect on the contractile response to methacholine. Conclusions: 1) Ca2+ influx through the L-type channels may be the primary source of Ca2+ to stimulate in vivo phasic contractions. 2) Phosphatidylinositol hydrolysis enhances the stimulation of in vivo phasic contractions in the normal ileum. In the inflamed ileum, phosphatidylinositol hydrolysis may be essential to stimulate phasic contractions. 3) Inflammation may downregulate the protein kinase C pathway. 4) Ryanodine stimulates phasic contractions by the release of ACh.",
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