Fig. 1.

The contractile responses of rat and mouse airways to methacholine (MCh), serotonin (5-HT), and KCl. A: typical phase-contrast images showing lung slices cut from rat (1 and 2) and mouse (3 and 4) in a resting state (1 and 3) and after 5 min of exposure to 200 nM MCh (2 and 4). B: representative experiments showing the change in airway lumen area of rat and mouse with respect to time in response to 200 nM MCh, 100 nM 5-HT, and 50 mM KCl. C: summary of MCh- (left) and 5-HT- (right) induced airway contraction in rats (black squares fitted with black solid line) and mice (gray circles fitted with gray dotted line). Contraction was measured as the decrease in lumen area after 5 min of agonist exposure. Each point represents the mean ± SE from at least 7 experiments from different slices from at least 4 rats and 5 experiments from 3 mice.