We will investigate trophic influences on the corneal epithelium by studying, physiologically, pharmacologically and biochemically, the pathways that are mediated by cyclic AMP in this tissue. Specific agents will be used that alter the cyclic AMP metabolism of the cornea such as: catecholamines, prostaglandins, cyclic AMP analogues, beta-adrenergic antagonists, phosphodiesterase inhibitors and cholera toxin. The influences of these agents on wound healing, mitotic rate, glycogen metabolism and the beta-adrenergic receptor population will be documented. To determine the potential for endogenous regulation of this pathway, the catecholamine level of tears will be investigated. Furthermore, results from in vivo experiments will be compared to those from in vitro experiments with cell culture of corneal epithelium.