Figure 3.

Increased carrageenan (CAR)-induced lung tissue damage in old rats. (a) Nitrite and nitrate exudate levels. (b) Nitrotyrosine immunohistochemical localization at 4 and 24 hr after carrageenan administration. Nitrite and nitrate exudate levels (a) in carrageenan-treated old rats were significantly increased relative to levels in young treated rats. Data are mean ± standard error of mean (SEM) for five rats for each group. The Bonferroni multiple comparison test was performed, with *P < 0·05 vs. vehicle-treated rats, and §P < 0·05 vs. young animals treated with carrageenan. Representative immunostaining of lung tissue sections obtained from carrageenan-treated young rats with antinitrotyrosine antibody (b, parts A and C) showed intense positive staining in inflammatory cells and around the vessels. Immunostaining for nitrotyrosine (b, parts B and D) was significantly higher in tissue sections obtained from old animals treated with carrageenan. Magnification: × 61.25.