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HERO ID
1654560
Reference Type
Journal Article
Title
Oxygen dependence of mitochondrial nitric oxide synthase activity
Author(s)
Alvarez, S; Valdez, LB; Zaobornyj, T; Boveris, A
Year
2003
Is Peer Reviewed?
Yes
Journal
Biochemical and Biophysical Research Communications
ISSN:
0006-291X
EISSN:
1090-2104
Volume
305
Issue
3
Page Numbers
771-775
Language
English
PMID
12763059
DOI
10.1016/S0006-291X(03)00818-0
Web of Science Id
WOS:000183355500048
Abstract
The effect of O(2) concentration on mitochondrial nitric oxide synthase (mtNOS) activity and on O(2)(-) production was determined in rat liver, brain, and kidney submitochondrial membranes. The K(mO(2)) for mtNOS were 40, 73, and 37 microM O(2) and the V(max) were 0.51, 0.49, and 0.42 nmol NO/minmg protein for liver, brain, and kidney mitochondria, respectively. The rates of O(2)(-) production, 0.5-12.8 nmol O(2)(-)/minmg protein, depended on O(2) concentration up to 1.1mM O(2). Intramitochondrial NO, O(2)(-), and ONOO(-) steady-state concentrations were calculated for the physiological level of 20 microM O(2); they were 20-39 nM NO, 0.17-0.33 pM O(2)(-), and 0.6-2.2 nM ONOO(-) for the three organs. These levels establish O(2)/NO ratios of 513-1000 that correspond to physiological inhibitions of cytochrome oxidase by intramitochondrial NO of 16-25%. The production of NO by mtNOS appears as a regulatory process that modulates mitochondrial oxygen uptake and cellular energy production.
Keywords
mtNOS; nitric oxide; superoxide radical; peroxynitrite; tissue oxygen
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