ASL measurements in well-differentiated HBE cell cultures. (A; left) SLRM images of ASL at three locations in an HBE culture 6 h after rinsing and the addition of 20 µl buffer. Dashed line indicates ASL surface. Bar, 10 µm. (Middle) Corresponding intensity versus distance profiles perpendicular to laser line. (Right) Confocal imaging showing ASL (red) and epithelium (green) under same conditions as in A. Bar, 10 µm. Corresponding fluorescence z-profile and ASL depth number histogram shown below image. (B) Time course of ASL depth after the addition of 20 µl buffer in untreated HBE cells measured by SLRM (circles, red lines) and z-scanning confocal microscopy (squares), and by SLRM after treatment with 100 µM amiloride. Mean ± SEM of three cell inserts. (C) SLRM image of unperturbed native ASL from HBE cells, with corresponding intensity profile shown below. Bar, 10 µm. (D) Surface plot of ASL depth in native HBE cells. (E) Summary of ASL depths measured by SLRM. Mean ± SEM of three cell inserts.