Ion transport in isolated cornea of the rabbit

¹ Ophthalmological Research Unit, Wilmer Institute, Johns Hopkins University Medical School, Baltimore, Maryland

When the isolated rabbit cornea is bathed with well-stirred normal Ringer solution, only a low potential difference (PD) exists across the tissue; the initial value of 2 mv rises to 6 mv (endothelium positive) 1 hr after excision from the animal. In sodium-free Ringer solution the PD becomes negative before becoming negligible, while in chloride-free Ringer the PD rises to triple the value in normal Ringer. Flux measurements of sodium 22 show that there is an initial inequality between the net flux and the measured short-circuit current (SCC), the values of which become equal 1 hr after removal of the cornea from the animal Flux measurements of chloride 36 during this 1st hr indicate an active transport of chloride inward across the cornea, but after 1 hr the fluxes are equal in each direction. The differences of the net currents generated by the sodium and chloride transports equal the measured SCC, and the two transports have been shown to be able to exist independently.

Key Words: active sodium transport • active chloride transport • bioelectrical potentials • transmembrane ion exchange

Submitted on April 5, 1965