Effect of exogenous ATP on canine jejunal smooth muscle

L. Xue, G. Farrugia, J. H. Szurszewski

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Intracellular recordings were made from the circular smooth muscle cells of the canine jejunum to study the effect of exogenous ATP and to compare the ATP response to the nonadrenergic, noncholinergic (NANC) inhibitory junction potential (IJP) evoked by electrical field stimulation (EFS). Under NANC conditions, exogenous ATP evoked a transient hyperpolarization (6.5 ± 0.6 mV) and EFS evoked a NANC IJP (17 ± 0.4 mV). ω-Conotoxin GVIA (100 nM) and a low-Ca2+, high-Mg2+ solution abolished the NANC IJP but had no effect on the ATP-evoked hyperpolarization. The ATP-evoked hyperpolarization and the NANC IJP were abolished by apamin (1 μM) and N(G)-nitro-L-arginine (100 μM). Oxyhemoglobin (5 μM) partially (38.8 ± 5.5%) reduced the amplitude of the NANC IJP but had no effect on the ATP-evoked hyperpolarization. Neither the NANC IJP nor the ATP-evoked hyperpolarization was affected by P2 receptor antagonists or agonists, including suramin, reactive blue 2, 1-(N,O-bis-[5- isoquinolinesulfonyl]-N-methyl-L-tyrosyl)-4-phenylpiperazine, pyridoxal phosphate-6-azophenyl-2',4'disulfonic acid, α,β-methylene ATP, 2- methylthioadenosine 5'-triphosphate tetrasodium salt, and adenosine 5'-O-2- thiodiphosphate. The data suggest that ATP evoked an apamin-sensitive hyperpolarization in circular smooth muscle cells of the canine jejunum via local production of NO in a postsynaptic target cell.

Original languageEnglish (US)
Pages (from-to)G725-G733
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume278
Issue number5 41-5
DOIs
StatePublished - May 2000

Keywords

  • Inhibitory innervation
  • Nitric oxide
  • Nonadrenergic
  • Noncholinergic inhibitory junction potential
  • Small intestine

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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