Release of nitric oxide and nitrosative stress in primary brain pericytes after LPS stimulation. Brain pericytes were stimulated for 4, 8, and 24 h with LPS (0.1 and 1 ug/ml), media collected, and analyzed for NO production by the Griess reaction. LPS (0.1 ug/ml and 1 μg/ml) induced a significant NO release from cells after 8 and 24 hours (A). Nitrative stress was accompanied by massive S-nitrosylation of cellular proteins (B). Values of nitrite accumulation from treated cells represent the mean ± SEM of two independent experiments conducted in tetraplicates. *P < 0.05, **P < 0.01, ***P < 0.001 vs. untreated cells.