Ketamine inhibits nitric oxide synthase in lipopolysaccharide-treated rat alveolar macrophages.
OBJECTIVE
To evaluate the effects of ketamine on the activity and protein expression of inducible nitric oxide synthase (iNOS) induced by lipopolysaccharide (LPS) in rat alveolar macrophages.


METHODS
Pulmonary alveolar macrophages isolated from Wistar-Kyoto rats were used. After incubation of macrophages with ketamine (1, 10, or 100 microM) and LPS (1 microgram.ml-1) for 24 hr, the cell-free medium was removed for measuring the nitrite and tumour necrosis factor-alpha (TNF-alpha) levels by Griess reaction and ELISA kit, respectively. The harvested macrophages were also used to determine the activity of iNOS by using the conversion of [3H]-L-arginine to [3H]-L-citrulline method. In addition, the protein expression of iNOS was detected by Western blot analysis.


RESULTS
In rat alveolar macrophages, (i) ketamine (1 to 100 microM) caused a dose-dependent suppression of the production of nitrite and TNF-alpha induced by LPS and (ii) ketamine (100 microM) inhibited the activity (46.5 +/- 4.8%, P < 0.05) and protein expression (35 +/- 11%, P < 0.05) of iNOS in response to LPS.


CONCLUSIONS
These results show that ketamine inhibits the activity and expression of iNOS in LPS-activated alveolar macrophages, which may be associated with the reduction of the release of TNF-alpha following LPS treatment.
Li
C Y
CY
Department of Anesthesiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China. cyli@ndmcl.ndmctsgh.edu.tw
Chou
T C
TC
Wong
C S
CS
Ho
S T
ST
Wu
C C
CC
Yen
M H
MH
Ding
Y A
YA
D000704:Analysis of Variance; D000778:Anesthetics, Dissociative / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001120:Arginine / Q000378:metabolism; D015153:Blotting, Western; D019069:Cell Respiration / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002956:Citrulline / Q000096:biosynthesis; D003470:Culture Media / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D015971:Gene Expression Regulation, Enzymologic; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D019001:Nitric Oxide Synthase / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000235:genetics; D009573:Nitrites / Q000032:analysis / Q000378:metabolism; D019275:Radiopharmaceuticals; D051381:Rats; D011921:Rats, Inbred WKY; D014316:Tritium; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000096:biosynthesis
D000778:Anesthetics, Dissociative; D003470:Culture Media; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D009573:Nitrites; D019275:Radiopharmaceuticals; D014409:Tumor Necrosis Factor-alpha; D014316:Tritium; D002956:Citrulline; D007649:Ketamine; D001120:Arginine; D019001:Nitric Oxide Synthase