Interleukin-1 induced nitric oxide production modulates glutathione
synthesis in cultured rat hepatocytes.
Kuo, Paul C., Keith Y. Abe, Rebecca A. Schroeder.
Dept. of Surgery, University of Maryland, Baltimore, MD, Dept. of
Surgery, Stanford University, Stanford, CA
APStracts 3:0103C, 1996.
In cultured rat hepatocytes, we have previously demonstrated that
inhibition of interleukin-1 (IL-1) mediated NO synthesis is
associated with depletion of intracellular reduced glutathione (GSH)
in toxin-mediated oxidative injury. To further examine NO's effects
on GSH metabolism in rat hepatocytes, IL-1 mediated NO synthesis was
examined in the context of: 1) cysteine, cystine and methionine
uptake, 2) gene transcription and enzyme activities for gamma
-glutamylcysteine synthetase, the rate-limiting enzyme in GSH
synthesis, glutathione reductase, and glutathione peroxidase, and 3)
GSH and oxidized glutathione (GSSG) levels. Inhibition of NO
synthesis decreased the GSH content and GSH/GSSG ratio in a guanylyl
cyclase-independent fashion. Enzyme activity and steady state levels
of mRNA for gamma-glutamylcysteine synthetase were also depressed.
Nuclear run-on analysis demonstrated ablation of gamma
-glutamylcysteine synthetase gene transcription. Hepatocellular uptake
of cysteine, cystine and methionine was not altered. Activity and
steady state mRNA levels for glutathione reductase and glutathione
peroxidase were not affected. These results indicate that IL-1
-mediated NO synthesis regulates hepatocyte GSH synthesis through a
mechanism that is dependent upon transcriptional regulation of the
rate limiting enzyme in GSH synthesis. In the setting of oxidative
stress and IL-1 exposure, hepatocyte synthesis of NO may be
protective through regulation of GSH synthesis.
Received 18 January 1996; accepted in final form 19 March 1996.
APS Manuscript Number C28-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96