Water permeability of the toad corneal epithelium: the effects of pH and amphotericin B.

The water diffusional permeability of the toad cornea was evaluated from THO measurements, while taking into account the influence of unstirred layers. The corneal epithelium is a restrictive barrier for water diffusion and its permeability can be increased by amphotericin B or Triton X-100. In animals maintained in tap water, the epithelial water permeability was reversibly inhibited by the acidification of the solution bathing the tear side of the cornea. When toads were adapted to a saline environment, a reduction of epithelial water permeability with a loss of sensitivity to changes in the tear side medium pH was observed.