Enterotoxin Escherichia coli STa activates a nitric oxide-dependent myenteric plexus secretory reflex in the rat ileum.
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.
Rolfe
V
V
Department of Biomedical Science, University of Sheffield.
Levin
R J
RJ
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001427:Bacterial Toxins / Q000494:pharmacology*; D004594:Electrophysiology; D004768:Enterotoxins / Q000494:pharmacology*; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D006652:Histological Techniques; D007082:Ileum / Q000187:drug effects / Q000294:innervation* / Q000502:physiology; D007413:Intestinal Mucosa / Q000187:drug effects / Q000502:physiology; D008297:Male; D009197:Myenteric Plexus / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology; D013268:Stimulation, Chemical; D013779:Tetrodotoxin / Q000494:pharmacology
D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D009569:Nitric Oxide; D012701:Serotonin; D013779:Tetrodotoxin; D001120:Arginine; C027538:heat-labile enterotoxin, E coli; D019331:NG-Nitroarginine Methyl Ester