Nitric oxide levels from young and aged mouse BMM in response to Pg. NO present in cell culture supernatant fluids from mouse BMM of 2-months (n = 6), 1-year (n = 3) and 2-years (n = 3) of age. BMM were cultured with Pg 381 (filled bars), Pg DPG3 (gray bars) at multiplicity of infection (MOI) of 100, or medium only control (open bars) for 24 h. Secreted NO levels were inferred by measuring μM nitrite levels using Greiss reaction as previously described . Asterisks indicate statistically significant (P < 0.05) as determined by Two way ANOVA with Bonferroni post-test analysis. NS = not significant.