Enterotoxin Escherichia coli STa activates a nitric oxide-dependent myenteric plexus secretory reflex in the rat ileum

J Physiol. 1994 Mar 15;475(3):531-7. doi: 10.1113/jphysiol.1994.sp020091.


1. Mucosally added enterotoxin Escherichia coli STa increased the electrogenic Cl- secretion measured as the short-circuit current (Isc) across isolated muscle-stripped and muscle-unstripped rat mid-ilea incubated in vitro. 2. Pretreatment with serosal L-NAME (N omega-nitro-L-arginine methyl ester) or tetrodotoxin (TTX) significantly reduced the maximum Isc and the duration of action of STa in the unstripped but not stripped ilea. D-NAME (serosal), indomethacin or 5-hydroxy-tryptamine-desensitization was ineffective on STa-induced Isc in either stripped or unstripped ilea. 3. Serosal capsaicin reduced the maximum Isc of STa and its duration of action in unstripped ilea. 4. L-Arginine induced a significantly larger increase in the Isc across unstripped ilea than across stripped ilea; this could be significantly reduced by serosal L-NAME or TTX, although these were ineffective in stripped ilea. 5. Pretreatment of anaesthetized rats with I.P. L-NAME suppressed the fluid secretion induced by luminal STa in ilea in vivo but had no effect on that induced by luminal carbachol. 6. Mucosal STa increased electrogenic Cl- secretion across intact rat ileum in vitro by activating a capsaicin-sensitive, nitric oxide-dependent myenteric plexus-mediated secretory reflex. The suppression by L-NAME of STa induced ileal fluid secretion in vivo probably involves the inhibition of this reflex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arginine / analogs & derivatives
  • Arginine / pharmacology
  • Bacterial Toxins / pharmacology*
  • Electrophysiology
  • Enterotoxins / pharmacology*
  • Escherichia coli
  • Escherichia coli Proteins*
  • Histological Techniques
  • Ileum / drug effects
  • Ileum / innervation*
  • Ileum / physiology
  • Intestinal Mucosa / drug effects
  • Intestinal Mucosa / physiology
  • Male
  • Myenteric Plexus / metabolism*
  • NG-Nitroarginine Methyl Ester
  • Nitric Oxide / physiology*
  • Rats
  • Rats, Inbred Strains
  • Reflex / drug effects*
  • Serotonin / pharmacology
  • Stimulation, Chemical
  • Tetrodotoxin / pharmacology


  • Bacterial Toxins
  • Enterotoxins
  • Escherichia coli Proteins
  • Nitric Oxide
  • Serotonin
  • Tetrodotoxin
  • Arginine
  • heat-labile enterotoxin, E coli
  • NG-Nitroarginine Methyl Ester