Permeability of the corneal endothelium to nonelectrolytes.

The endothelial surface of the isolated rabbit cornea was perfused with modified KEI medium, according to the method reported previously. This in vitro cornea maintained its thickness within the normal range even after the epithelium ivas removed. The endothelial permeability of these in vitro corneas to tritiated water, >C-labeled urea, sucrose, and inulin teas determined. The reflection coefficients of the endothelium calculated according to the physical interpretation of Kedem and Katchalsky were in fair agreement with those determined previously from osmotic fluid flow across the endothelium. Perfusion of the corneal endothelium with calciumfree KEI medium resulted in a corneal swelling with an increased endothelial permeability. Perfusion with KEI medium containing ouabain (10~ and 10~ moles per liter) induced a corneal swelling with normal endothelial permeability.