Figure 1.

Methacholine dose–response relationships for airway resistance (R) and tissue stiffness (H) for the four groups of BALB/c mice. R is the peak value observed following each challenge. H is the final plateau value observed 5 minutes after each challenge. Allergically inflamed mice treated with 100 μg poly-l-lysine (PLL) died almost immediately after being challenged with the lowest dose of methacholine. Mice treated with the lower dose of 30 μg PLL, either alone or in combination with ovalbumin (Ova) sensitization and challenge, survived challenge with all doses of methacholine. The values of R in the PLL (30 μg)+Ova group were significantly greater (P < 0.05, unpaired t test) than their respective values in each of the naive, PLL, and Ova groups, with the exception of the Ova group at baseline and 3.125 mg/ml methacholine. The values of H in the PLL+Ova group were significantly greater than those in the other three groups at all methacholine concentrations.