The mechanisms involved in lowering intraocular pressure (IOP) in glaucoma therapy have not been fully explained. This grant proposes to examine the cells involved in aqueous humor secretion to attempt a better explanation for effects seen in IOP regulation. The eye appears to have unique properties for the production and regulation of aqueous humor inflow. An understanding of therapeutic drug interactions with specific cells of the inflow pathway (especially the ciliary epithelium) could lead to improved glaucoma therapy. Pharmacologic compounds which lower intraocular pressure, in which an inflow mechanism appears likely, will be investigated by evaluating specific molecular properties of the cell membrane; in so doing, we hope to better understand the underlying mechanisms for physiological regulation and for drug effects over aqueous humor secretion. Cultured human ciliary epithelial cells (both non-pigmented and pigmented) and fresh tissue obtained from bovine sources will be analyzed in our initial studies using lipid bilayer technology, with other biochemical correlates which could explain secretory mechanisms. With this information we hope to develop an improved understanding of the molecular interactions which underlie the regulation of aqueous humor inflow.