Fig. 11. LAT treatment of lacrimal acini enhances CCH-stimulated secretion in parallel with depletion of apical actin filaments. (A) Confocal fluorescence micrographs of lacrimal acini fixed and processed for labeling of actin filaments as described in Materials and Methods. Treatments included untreated lacrimal acini (CON) and acini exposed to LAT B (10 µM, 15 minutes) in the absence (LAT) or presence (LAT + CCH) of CCH (100 µM, 15 minutes). *, Lumenal regions; bar, 5 µm. (B) Effects of LAT B on bulk protein secretion (left) and syncollin-GFP release (right) without or with CCH stimulation. Values were normalized to cell protein before comparison across samples. *Significant at P0.05 from paired control value; n=6 for protein release and n=3 for syncollin-GFP release. (C) Left, EM image at lower magnification from rabbit lacrimal acini exposed to LAT A (1 µM, 15 minutes) and right, boxed region at higher magnification. Arrowheads depict SVs at the APM that are beginning to fuse. (D) Images showing premature fusion of mSVs in LAT A-treated, unstimulated acini. L, lumenal region; SV, secretory vesicle; bars (C,D), 500 nm.