DISTRIBUTION OF THE PLASMALEMMAL CA2-PUMP AND CAVEOLIN IN THE CORNEALEPITHELIUM DURING THE WOUND-HEALING PROCESS()

Purpose. Caveolae are small plasmalemmal invaginations which are assum ed to play various physiological functions. In the present study, dist ribution of two caveolae-specific proteins, the plasmalemmal Ca2+-pump and caveolin, was examined in the corneal epithelium in the normal st ate and after artificial wounding. Methods. A central epithelial ablat ion was made in the mouse cornea by a razor blade. After various inter vals, the corneas were excised, fixed, and rapidly frozen. The specime ns were subjected to immunofluorescence microscopy and immunoelectron microscopy, using antibodies against the plasmalemmal Ca2+-pump or cav eolin. Results. In the normal corneal epithelium, both plasmalemmal Ca 2+-pump and caveolin were observed along the cell surface by immunoflu orescence microscopy, and were localized to caveolae by immunogold ele ctron microscopy. In the regenerating epithelium, 12-18 h after injury , plasmalemmal Ca2+-pump was seen as many dots in the cytoplasm by imm unofluorescence microscopy; in contrast, caveolin persisted along the cell surface. Immunoelectron microscopy revealed that the labeling for the plasmalemmal Ca2+-pump was located around membranous structures i n the cytoplasm and was scarce along the plasma membrane, while caveol in remained in caveolae. The Ca2+-pump regained normal distribution wh en the wound was closed. By quantitation in electron micrographs, the number of caveolae per unit plasma membrane length was found to be dec reased in the wounded corneal epithelium. Conclusions. The present res ults indicate that caveolae undergo compositional modification during the wound healing process of the corneal epithelium. Considering putat ive caveolar functions, the phenomenon may be related to possible fluc tuations of the intracellular Ca2+ concentration in the regenerating e pithelium.