Different corneal epithelial healing mechanisms in rat and rabbit: role of actin and calmodulin

The authors investigated the effects of calmodulin inhibitors, trifluoperazine (10-20 microM) and W-7 (25-50 microM), and of cytochalasin B (5 micrograms/ml) on the F-actin distribution, surface morphology, and migration of rat and rabbit corneal epithelial cells in tissue culture. In the rat, actively migrating cells have abundant F-actin-containing stress fibers and numerous cytoplasmic extensions of the plasmalemma. These features, and ultimately cell migration, are inhibited by calmodulin inhibitors and cytochalasin B. In the rabbit, migrating cells are devoid of stress fibers and cytoplasmic extensions. Cell migration is not inhibited by calmodulin inhibitors but is arrested by cytochalasin B. The cell-to-substrate adhesion is reduced by calmodulin inhibitors in both rat and rabbit. These findings corroborate our earlier observations in organ culture studies and support the view that corneal epithelial cell migration is calmodulin-dependent in the rat, while it is not in the rabbit. The complete blockage of migration in both species by cytochalasin B suggests that actin polymerization is critical for corneal epithelial locomotion in both species.