Glucocorticoids do not affect the induction of a novel calcium-dependent nitric oxide synthase in rabbit chondrocytes.
Incubation of rabbit articular chondrocytes with interleukin-1 beta caused time-dependent expression of NO synthase, determined as nitrite, after a lag period of 6h. The synthesis of nitrite was concentration-dependent and was inhibited by cycloheximide and NG-monomethyl-L-arginine, but not by dexamethasone or hydrocortisone. The synthesis of NO in the 100,000g supernatant of activated chondrocytes was inhibited by EGTA, but not by the calmodulin inhibitors W-13 or trifluoperazine. The synthesis of NO was half-maximal at approximately 20nM free Ca2+. Endotoxin also induced the expression of this NO synthase. Thus, rabbit articular chondrocytes express a novel inducible NO synthase which is Ca(2+)-dependent, and whose induction is not prevented by glucocorticoids.
Palmer
R M
RM
Wellcome Research Laboratories, Beckenham, Kent, U.K.
Andrews
T
T
Foxwell
N A
NA
Moncada
S
S
D000594:Amino Acid Oxidoreductases / Q000096:biosynthesis* / Q000378:metabolism; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002358:Cartilage, Articular / Q000187:drug effects / Q000201:enzymology*; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D004790:Enzyme Induction; D006854:Hydrocortisone / Q000494:pharmacology*; D007213:Indomethacin / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D019001:Nitric Oxide Synthase; D011817:Rabbits; D013449:Sulfonamides / Q000494:pharmacology; D014268:Trifluoperazine / Q000494:pharmacology; D019323:omega-N-Methylarginine
D002147:Calmodulin; D007375:Interleukin-1; D013449:Sulfonamides; D014268:Trifluoperazine; D019323:omega-N-Methylarginine; D004533:Egtazic Acid; D003907:Dexamethasone; C033772:N-(4-aminobutyl)-5-chloro-2-naphthalenesulfonamide; D001120:Arginine; D003513:Cycloheximide; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D002118:Calcium; D006854:Hydrocortisone; D007213:Indomethacin