Inhibition of active transport of chloride and sodium by vanadate in the cornea

Vanadate, an inhibitor of (Na⁺ + K⁺)ATPase, also inhibits active transepithelial Na⁺ and Cl^- transport (measured as short-circuit current) in the isolated cornea in concentrations of 10^-4M to 10^-3M. The disulfonic stilbene, DIDS, does not affect the short-circuit current per se, but it prevents the inhibitory effect of vanadate on Na⁺ and Cl^- transport. Since vanadate acts in other systems from the cytoplasmic side, it is postulated that DIDS interferes with vanadate penetration into the epithelial cells. These results also strengthen the notion of a Na-Cl co-transport system in the corneal epithelium.