Dantrolene inhibits nitric oxide synthase in rat alveolar macrophages treated with lipopolysaccharide and interferon-gamma.
OBJECTIVE
To examine the effects of dantrolene on nitric oxide (NO) production and on the activity and protein expression of inducible nitric oxide synthase (iNOS) induced by lipopolysaccharide (LPS) plus interferon-gamma (IFN gamma) in rat alveolar macrophages.


METHODS
Pulmonary alveolar macrophages isolated from Sprague-Dawley rats were used. After incubation of macrophages with dantrolene (1 to 100 microM) and LPS (1 microgram.ml-1) and IFN-gamma (100 u.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. Protein expression of iNOS was detected by Western blot analysis.


RESULTS
In rats alveolar macrophages, (i) dantrolene (1 to 100 microM) caused a dose-dependent suppression of the production of nitrite and TNF-alpha induced by LPS (1 microgram.ml-1) plus IFN-gamma (100 u.ml-1) and (ii) dantrolene (100 microM) inhibited the activity (by 37 +/- 5%, P < 0.01) and protein expression (by 39 +/- 12%, P < 0.01) of iNOS in response to LPS plus IFN-gamma.


CONCLUSIONS
Dantrolene inhibits NO production as well as the activity and expression of iNOS in alveolar macrophages treated with LPS plus IFN-gamma, which may be associated with the reduction of TNF-alpha production.
Li
C Y
CY
Department of Anesthesiology, Graduate Institute of Medical Sciences, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China. cyli@ndmc1.ndmctsgh.edu.tw
Chou
T C
TC
Wu
C C
CC
Wong
C S
CS
Ho
S T
ST
Yen
M H
MH
Ding
Y A
YA
D000818:Animals; D015153:Blotting, Western; D019069:Cell Respiration / Q000187:drug effects; D002474:Cell-Free System; D003620:Dantrolene / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D009125:Muscle Relaxants, Central / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D009125:Muscle Relaxants, Central; D009573:Nitrites; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D003620:Dantrolene