Induction of superoxide in glioma cell line U87 stimulated with lipopolysaccharide and interferon-gamma: ESR using a new flow-type quartz cell

The production of superoxide and nitric oxide induced in U87 glioma treated with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) was examine d by electron spin resonance (ESR) spectroscopy using a newly designed flow -type quartz cuvette without detaching tells from the culture plate. ESR sp ectra of 2,2,6,6-tetramethyl-4-hydroxy-1-piperidinyloxy(TEMPOL) with U87 ce lls on a quartz culture plate were measured at 15 min intervals. The signal intensity of TEMPOL decreased in the presence of U87 cells at the pseudo-f irst order rate. The signal decay was accelerated in the U87 cells treated with LPS/IFN-gamma for 24 h, and was suppressed in the presence of superoxi de dismutase and catalase. By the spin-trapping method, nitric oxide from U 87 cells pretreated with LPS/IFN-gamma for 24 h was measured by the ESR, bu t only a weak signal of nitric oxide adducts was detected. Further, the nit rite and nitrate levels in the medium did not increase for 24 h, By the ESR measurement of cells on culture plates without detachment stress, it was f ound that the production of superoxide mas induced by LPS/IFN-gamma, but th at of nitric oxide was not, in U87 glioma cells. (C) 2000 Federation of Eur opean Biochemical Societies.