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Cultured astrocytoma cells generate a nitric oxide‐like factor from endogenous L‐arginine and glyceryl trinitrate: effect of E. coli lipopolysaccharide
Author(s) -
Salvemini Daniela,
Mollace Vincenzo,
Pistelli Alessandra,
Änggård Erik,
Vane John
Publication year - 1992
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1992.tb14437.x
Subject(s) - cycloheximide , sodium nitroprusside , omega n methylarginine , arginine , nitric oxide , lipopolysaccharide , chemistry , incubation , superoxide dismutase , guanosine , biochemistry , pharmacology , microbiology and biotechnology , endocrinology , biology , enzyme , amino acid , protein biosynthesis , organic chemistry
1 The inhibitory activity of astrocytoma cells (0.25–3 × 10 5 ) treated with indomethacin (10 μ m ) on platelet aggregation was enhanced by incubating the cells with E. coli lipopolysaccharide (LPS, 0.5 μg ml −1 ) for 18 h. This effect was attenuated when cycloheximide (10 μg 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 μ m ) or N G ‐monomethyl‐ l ‐arginine ( l ‐NMMA, 30–300 μ m ). The effects of l ‐NMMA were reversed by co‐incubation with l ‐arginine ( l ‐Arg, 100 μ m ) but not d ‐arginine ( d ‐Arg, 100 μ m ). LPS also increased the levels of nitrite in the culture media and this increase was ablated by co‐incubation with l ‐NMMA (300 μ m ) or cycloheximide (10 μg ml −1 ). 2 Astrocytoma cells (0.5 × 10 5 ) treated with indomethacin (10 μ m ) enhanced the platelet inhibitory activity of glyceryl trinitrate (GTN, 11–352 μ m ) but not that of sodium nitroprusside (4 μ m ). Furthermore, when incubated with GTN (200 μ m ) 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 μ m ) but not with l ‐NMMA (300 μ m ). Treatment of the cells with LPS (0.5 μg 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.