The induction of nitric oxide synthase and intestinal vascular permeability by endotoxin in the rat

Nigel K. Boughton‐Smith, Steven M. Evans, Ferenc Laszlo, Brendan J.R. Whittle, Salvador Moncada

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The effect of endotoxin (E. coli lipopolysaccharide) on the induction of nitric oxide synthase (NOS) and the changes in vascular permeability in the colon and jejunum over a 5 h period have been investigated in the rat. Under resting conditions, a calcium‐dependent constitutive NOS, determined by the conversion of radiolabeled l‐arginine to citrulline, was detected in homogenates of both colonic and jejunal tissue. Administration of endotoxin (3 mg kg−1, i.v.) led, after a 2 h lag period, to the appearance of calcium‐independent NOS activity in the colon and jejunum ex vivo, characteristic of the inducible NOS enzyme. Administration of endotoxin led to an increase in colonic and jejunal vascular permeability after a lag period of 3 h, determined by the leakage of radiolabelled albumin. Pretreatment with dexamethasone (1 mg kg−1 s.c., 2 h prior to challenge) inhibited both the induction of NOS and the vascular leakage induced by endotoxin. Administration of the NO synthase inhibitor NG‐monomethyl‐l‐arginine (12.5–50 mg kg−1, s.c.) 3 h after endotoxin injection, dose‐dependently reduced the subsequent increase in vascular permeability in jejunum and colon, an effect reversed by l‐arginine (300 mg kg−1, s.c). These findings suggest that induction of NOS is associated with the vascular injury induced by endotoxin in the rat colon and jejunum. 1993 British Pharmacological Society

Original languageEnglish
Pages (from-to)1189-1195
Number of pages7
JournalBritish journal of pharmacology
Issue number3
Publication statusPublished - Nov 1993



  • NO synthase inhibitor
  • Nitric oxide
  • N‐monomethyl‐l‐arginine
  • corticosteriods
  • endotoxin
  • inducible nitric oxide synthase
  • intestinal inflammation
  • vascular permeability

ASJC Scopus subject areas

  • Pharmacology

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