Active transport of chloride in frog cornea

Abstract

The transparency of the cornea apparently depends on a metabolic process linked to an active ion transport. In the isolated cornea of the bullfrog, Rana catesbiana, chloride ions were found to be transported from aqueous to tear side (endothelium to epithelium). Measurements of short-circuit current and radioisotopic fluxes of chloride and Na indicate that Na behaves as a passive ion and that the current is produced only by the chloride transport. The chloride transport follows Michaelis-Menten kinetics between 0 and 100 m[image] chloride; it is inhibited by cold, and it is highly dependent on the presence of Na ions in the bathing fluids. The possible relationships among this chloride transport and the swelling and opacity of the cornea are discussed.