Cultured astrocytoma cells generate a nitric oxide-like factor from endogenous L-arginine and glyceryl trinitrate: effect of E. coli lipopolysaccharide.
1. The inhibitory activity of astrocytoma cells (0.25-3 x 10(5)) treated with indomethacin (10 microM) on platelet aggregation was enhanced by incubating the cells with E. coli lipopolysaccharide (LPS, 0.5 micrograms ml-1) for 18 h. This effect was attenuated when cycloheximide (10 micrograms ml-1) was incubated together with LPS. The inhibition of platelet aggregation by cells treated with LPS was potentiated by superoxide dismutase (60 u ml-1) and ablated by oxyhaemoglobin (oxyHb, 10 microM) or NG-monomethyl-L-arginine (L-NMMA, 30-300 microM). The effects of L-NMMA were reversed by co-incubation with L-arginine (L-Arg, 100 microM) but not D-arginine (D-Arg, 100 microM). LPS also increased the levels of nitrite in the culture media and this increase was ablated by co-incubation with L-NMMA (300 microM) or cycloheximide (10 micrograms ml-1). 2. Astrocytoma cells (0.5 x 10(5)) treated with indomethacin (10 microM) enhanced the platelet inhibitory activity of glyceryl trinitrate (GTN, 11-352 microM) but not that of sodium nitroprusside (4 microM). Furthermore, when incubated with GTN (200 microM) a 4 fold increase in the levels of guanosine 3':5'-cyclic monophosphate (cyclic GMP) was observed. These effects were abrogated by co-incubation with oxyHb (10 microM) but not with L-NMMA (300 microM). Treatment of the cells with LPS (0.5 micrograms ml-1) for 18 h did not enhance their capacity to form NO from GTN. 3. Thus, in cultured astrocytoma cells, LPS enhances the formation of nitric oxide from endogenous L-arginine.In addition, these cells can metabolize GTN to nitric oxide but this process is not enhanced by LPS stimulation.
Salvemini
D
D
William Harvey Research Institute, St Bartholomew's Hospital Medical College, Charterhouse Square, London.
Mollace
V
V
Pistelli
A
A
Anggård
E
E
Vane
J
J
D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D001254:Astrocytoma / Q000378:metabolism*; D006152:Cyclic GMP / Q000032:analysis; D004926:Escherichia coli; D006801:Humans; D007213:Indomethacin / Q000494:pharmacology; D008070:Lipopolysaccharides; D009569:Nitric Oxide / Q000378:metabolism*; D005996:Nitroglycerin / Q000378:metabolism*; D010974:Platelet Aggregation / Q000187:drug effects; D014407:Tumor Cells, Cultured; D019323:omega-N-Methylarginine
D008070:Lipopolysaccharides; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine; D005996:Nitroglycerin; D006152:Cyclic GMP; D007213:Indomethacin