Induction and activity of nitric oxide synthase in cultured human
intestinal epithelial monolayers.
Salzman, Andrew L., Alvin G. Denenberg, Ikuya Ueta, Michael O'connor,
Stephen C. Linn, and Csaba Szab[acute]o.
Division of Critical Care, Children's Hospital Medical Center, 3333
Burnet Avenue, Cincinnati, Ohio 45229
APStracts 2:0215G, 1995.
We have examined the induction and activity of inducible nitric oxide
(NO) synthase (iNOS) in monolayers of DLD-1 cells, an epithelial cell
line derived from a human intestinal adenocarcinoma. Induction of
iNOS transcription by a combination of the cytokines IFN-[gamma] and
IL-1[beta] was inhibited by genestein, pyrrolidine dithiocarbamate,
or dexamethasone, and unaffected by pretreatment with EGTA, basic
fibroblast growth factor (bFGF), epidermal growth factor (EGF), or
the isoflavone daidzein. iNOS activity and NO synthesis were
inhibited by L-NAME, L-NMMA, S-methyl-isothiourea sulfate, or
aminoethyl-isothiourea, but not by dexamethasone. NO synthesis was
potently inhibited by N-[alpha]-p-tosyl-lysine chloromethyl ketone
and hypoxia. In the absence of cytokines, no iNOS induction was
observed with oxidant stress (H2O2), growth factors (bFGF, EGF),
hypoxia, or hypoxia-reoxygenation. We conclude that, in this model of
the human intestinal epithelium, 1) cytokine-mediated induction of
iNOS is calcium-independent, weakly steroid sensitive, and may
involve the activation of NF-kB and a tyrosine kinase, and 2) iNOS
activity is calcium-independent and inhibited by hypoxia, NG
-substituted L-arginine analogues, and isothioureas.
Received 6 June 1995; accepted in final form 30 September 1995.
APS Manuscript Number G242-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95