Fig. 3.

Submucosal glands are major contributors to bacteria-stimulated ASL secretion. (A) Tracheas with submucosal glands (SMG) surgically removed produced less fluid than tracheas with intact SMG (n = 13 with SMG and n = 11 without SMG; P < 0.05, Student t test). Columns labeled with different letters differ significantly). (B) Bacteria-free and P. aeruginosa-laden agarose beads were differentially labeled with barium or iodine and detected using K-edge subtraction. ASL height was measured at each individual bead by a researcher blinded to the experimental conditions. Only bacteria-laden beads showed increases in ASL after a 35-min incubation. On average, there were eight agarose beads per trachea, and the average distance between beads was 1.6 mm. (C) Increase in ASL height after a 35-min concurrent instillation of bacteria-free and P. aeruginosa-laden agarose beads (n = 23 for both groups; P < 0.05, Student t test). Columns labeled with different letters differ significantly.