LEAD INHIBITS NITRIC-OXIDE PRODUCTION TRANSIENTLY BY MESSENGER-RNA LEVEL IN MURINE MACROPHAGE CELL-LINES

Lead inhibited the production of nitric oxide (NO) in cytokine-induced macrophage cell lines of RAW264 and Mml, The decrease was revealed in the concentration of lead (0.1-10 mu g/ml) which did not decrease the viability of these cells, The inhibition was proved to be due to the suppression of an inducible type of NO synthase (iNOS) mRNA expression in RAW264 cells. This suppression was found at 24h and then recovered to the control level (stimulated with cytokine alone) following cultu re, In the RAW264 cell line, the time course pattern of NO production corresponded to the iNOS mRNA expression, From these results, the inhi bition of NO production by, at least in part, mRNA level could be impl icated in lead-caused abnormalities in immune functions.