Figure 3. Age-associated increase in protein tyrosine nitration in the lungs during systemic inflammation.
Systemic inflammation was induced in young (4 months) and aged (24 months) mice by injection with LPS (2.5 mg/kg, ip); mice were sacrificed 6 and 12 h later and the lung tissues harvested for analysis. Age and sex-matched non-injected mice were used as controls. (A) Immunohistochemical localization of nitrotyrosine to the vasculature of aged mice after LPS injection. Arrows indicate strongly stained vascular endothelium. (B) Western blot analyses for nitrotyrosine on whole-lung proteins and densitometric analysis of each lane. Total intensity throughout each lane was normalized by β-actin. (C) Northern hybridization analysis demonstrating that induction of lung iNOS mRNA after LPS injection was augmented in aged mice compared to young mice. Young (4 months) and aged (24 months) mice were injected with LPS (2.5 mg/kg, ip) and total lung RNA was isolated and used for Northern blot analysis. Each lane represents a pooled protein sample derived equally from 5 mice.