Co‐induction of nitric oxide synthase and cyclo‐oxygenase: interactions between nitric oxide and prostanoids

1 Lipopolysaccharide (LPS) co‐induces nitric oxide synthase (iNOS) and cyclo‐oxygenase (COX‐2) in J774.2 macrophages. Here we have used LPS‐activated J774.2 macrophages to investigate the effects of exogenous or endogenous nitric oxide (NO) on COX‐2 in both intact and broken cell preparations. NOS a...

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Bibliographic Details
Published in:British journal of pharmacology 1995-04, Vol.114 (7), p.1335-1342
Main Authors: Swierkosz, Tomasz A., Mitchell, Jane A., Warner, Timothy D., Botting, Regina M., Vane, John R.
Format: Article
Language:English
Subjects:
Amino Acid Oxidoreductases - biosynthesis
Amino Acid Oxidoreductases - drug effects
Animals
Biological and medical sciences
Cells, Cultured
cyclo‐oxygenase
cytokine
Dose-Response Relationship, Drug
endotoxin
Enzyme Induction - drug effects
Fundamental and applied biological sciences. Psychology
Kidney - metabolism
Lipopolysaccharides - pharmacology
Lung - metabolism
Macrophages - drug effects
Macrophages - enzymology
Male
Mice
N-Methylaspartate - pharmacology
NADPH Dehydrogenase - biosynthesis
NADPH Dehydrogenase - drug effects
NG‐monomethyl‐L‐arginine
NG‐nitro‐L‐arginine
Nitric oxide
Nitric Oxide - pharmacology
Nitric Oxide Synthase
Nitroprusside - pharmacology
prostacyclin
Prostaglandin-Endoperoxide Synthases - drug effects
Prostaglandin-Endoperoxide Synthases - metabolism
Prostaglandins - pharmacology
Prostaglandins F - biosynthesis
Prostaglandins. Arachidonic acid metabolites
Rats
Rats, Wistar
Vertebrates: endocrinology
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Summary:1 Lipopolysaccharide (LPS) co‐induces nitric oxide synthase (iNOS) and cyclo‐oxygenase (COX‐2) in J774.2 macrophages. Here we have used LPS‐activated J774.2 macrophages to investigate the effects of exogenous or endogenous nitric oxide (NO) on COX‐2 in both intact and broken cell preparations. NOS activity was assessed by measuring the accumulation of nitrite using the Griess reaction. COX‐2 activity was assessed by measuring the formation of 6‐keto‐prostaglandin F1α (6‐keto‐PGF1α) by radioimmunoassay. Western blot analysis was used to determine the expression of COX‐2 protein. We have also investigated whether endogenous NO regulates the activity and/or expression of COX in vivo by measuring NOS and COX activity in the lung and kidney, as well as release of prostanoids from the perfused lung of normal and LPS‐treated rats. 2 Incubation of cultured murine macrophages (J774.2 cells) with LPS (1 μg ml−1) for 24 h caused a time‐dependent accumulation of nitrite and 6‐keto‐PGF1α in the cell culture medium which was first significant after 6h. The formation of both 6‐keto‐PGF1α and nitrite elicited by LPS was inhibited by cycloheximide (1 μm) or dexamethasone (1 μm). Western blot analysis showed that J774.2 macrophages contained COX‐2 protein after LPS administration, whereas untreated cells contained no COX‐2. 3 The accumulation of 6‐keto‐PGF1α in the medium of LPS‐activated J774.2 macrophages was concentration‐dependently inhibited by chronic (24 h) exposure to sodium nitroprusside (SNP; 1–1000 μm). Sodium nitroprusside (l‐1000μm) also acutely (30 min) inhibited COX‐2 activity in broken cell preparations of LPS‐activated (12 h) J774.2 macrophages, in a similar concentration‐dependent manner. Addition of adrenaline (5 mM) and glutathione (0.1 mM) increased the activity of COX‐2 in broken cell preparations. In the presence of these co‐factors, SNP inhibited prostanoid production only at the highest concentration used (1 mM). When J774.2 cells were incubated in the presence of LPS (1 μg ml−1) and NG‐monomethyl‐L‐arginine (L‐NMMA: 1 mM) for 12 h, SNP at the highest concentration used (1 mM) acutely (30 min) inhibited the activity of COX‐2 in cell homogenates with co‐factors. However, when J774.2 macrophages were incubated for 24 or 12 h with LPS (1 μg ml−1) and L‐NMMA (1 mM), the addition of SNP (0.001–1000 μm) increased in a concentration‐dependent manner the accumulation of 6‐keto‐PGF1α in intact cells (measured at 24 h) and COX‐2 activity in cell homogenates i
ISSN:0007-1188
1476-5381
DOI:10.1111/j.1476-5381.1995.tb13353.x