Elaboration of Bicarbonate Ion in Intraocular Fluids: I. Aqueous Humors, Following Intravenous Infusion of Sodium Bicarbonate

The dominant thinking prevailing with regard to the understanding of the dynamic properties of the aqueous humor arose chiefly from the classic experiments of Friedenwald and co-workers¹ and matured later in the form of the secretion-diffusion theory postulated by Kinsey.* Thus, hydroxyl ions are presumed to be generated continuously by the oxidation of reduced cytochrome oxidase in the epithelium of the ciliary processes. Neutralization of the hydroxyl ions by carbon dioxide is postulated as the source of the bicarbonate ion, which then diffuses into the posterior chamber, resulting in the excess of bicarbonate ion in this fluid compared with that in blood plasma. The net dynamic effect of such a distribution is considered responsible for the hypertonicity (equivalent to 3 mM. NaCl/liter) of the aqueous humor of the rabbit eye and the associated osmotic flow of fluid into the eye. The physiologic interplay of the forces responsible for the