Fig. 2.

Ovalbumin (OVA) treatment increases cholinergic airways responsiveness in BALB/c mice. A: time course of OVA sensitization and challenge. On day 0, mice were injected intraperitoneally (IP) with 1 mg of a sterile, endotoxin-free solution of OVA emulsified in 25% (wt/vol, final) alum suspension or an equivalent amount of alum alone for the PBS control group. On day 11, mice were given a similar IP injection as well as an intranasal (IN) inoculation with 1 mg of OVA dissolved in 50 μl of PBS or PBS alone. Mice were allowed to recover and inoculated again with IN PBS or OVA on days 18, 21, 22, and 23. Mice were studied on day 25. B: PBS-treated (▪) or OVA-treated (○) mice were examined for airways resistance using a positive displacement respirometer and increasing doses of nebulized methacholine in PBS (n = 3, means ± SE; *P < 0.05, 2-way ANOVA).