Figure 5.

ASL depth in mouse distal airways. (A) Representative fluorescence confocal images of TMR-dextran–stained ASL in distal airways of different diameters. Stained ASL (only one edge of airway) shown at high magnification. Airway diameters were 260, 200, 185, and 105 μm for a–d, respectively. Confocal images of red fluorescent latex beads of 9.7 and 3.7 μm diameter shown in e and f. (B) Fluorescence scans taken at indicated regions of ASL from images in a–d in A (dashed lines) along with fitted Gaussian functions (smooth curves). Scans taken through center of beads for e and f. (C, top) Fluorescence confocal image of glass micropipette coated with a submicron fluorescent layer (by dipping in chloroform containing dissolved green-fluorescing polystyrene beads). Inset shows low magnification wide-field fluorescence. (Bottom) Fluorescence confocal image taken at the center of concentric glass micropipettes sandwiching an annular fluorescent aqueous layer (TMR-dextran in water). Dashed lines show boundary of inner and outer micropipettes determined from brightfield micrographs as shown in the inset (lines with double arrows). Bars, 20 μm. (D) ASL depth as a function of airway diameter determined by reconvolution of scans as in B (open circles, control mice; closed circles, amiloride-treated mice). Differences in control versus amiloride-treated mice not significant.