Corneal epithelium is thought to be a functional syncytium due to the presence of gap junctions which form cell to cell channels through which small molecules pass. It is thought that intercellular communication is important for many of the biomedical and physiological processes that occur in all epithelia, but very little is known specifically about gap junctions in the cornea. This proposal outlines a pilot project study of gap junctions in corneal tissue. Specifically, the proposed experiments are designed to determine under what in vitro conditions coupling can be maintaining and modulated among the corneal epithelial cells and if the degree of coupling between cells in culture correlates with the physiologic response of intact epithelium to various factors. Cell cultures derived from rabbit corneal epithelium will be used for these experiments. Lucifer yellow CH or sulforhodamine B dyes will be iontophoresed into cells impaled with fine-tipped micropipets and the spread of the dye recorded on video tape with the aid of a SIT type video camera. We will look for quantitative differences in the transfer of the dye from cell to cell in response to changes in osmolality, oxygen, agents known to the stimulate chloride transport across the cornea and neuropeptides found in the corneal sensory nerve fibers. Results of these preliminary experiments will be used as the basis for further, more detailed research on the role and regulation of gap junctions in the corneal epithelium under normal and pathologic conditions.
