A technique to estimate the rate of whole body nitric oxide formation in conscious mice.
OBJECTIVE
We have established a technique to estimate the total rate of nitric oxide (NO) formation in mice, based on inhalation of a stable oxygen isotope (18O(2)). Changes of NO production with age were also studied.


METHODS
The experiments were performed in eight-week- (n=6) and eight-month-old (n=6-7), respectively, female (C57/Bl6xCBAca) mice. Pairs of conscious mice were kept in an air-tight closed system allowing breathing of a mixture containing 18O(2). The 18O(2)-technique was validated by L-NAME (10mg/kg) and lipopolysaccharide (LPS, 8 mg/kg) administration. The concentrations of O(2) and CO(2) in the system were controlled and plasma nitrate analyzed by GC/MS technique.


RESULTS
NO formation was similar in young and old mice (young=7.68+/-1.47 vs. old = 6.25+/-1.49 micromol/kg/h, n.s.). Total NO production was reduced after L-NAME treatment in young animals by 91% and in old animals by 71% (p<0.05 for both), whereas LPS administration increased NO production (114+/-17%, p<0.05).Conclusion. NO formation is unaltered with age in mice. The 18O(2)-technique is a valid and specific technique to estimate whole body NO production in conscious mice.
Wickman
Anna
A
Department of Physiology, Sahlgrenska Academy, Göteborg University, PO Box 432, S-405 30, Göteborg, Sweden. anna.wickman@fysiologi.gu.se
Klintland
Natalia
N
Gan
Li-ming
LM
Sakinis
Augustinas
A
Söderling
Ann-Sofie
AS
Bergström
Göran
G
Caidahl
Kenneth
K
D000818:Animals; D019540:Area Under Curve; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006207:Half-Life; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009566:Nitrates / Q000097:blood / Q000652:urine; D009569:Nitric Oxide / Q000096:biosynthesis*; D010103:Oxygen Isotopes
D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D009566:Nitrates; D010103:Oxygen Isotopes; D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester