Ascorbate transport in guinea pig eyes

Excised guinea pig ciliary body-iris preparations accumulated <C-labeled L-ascorbate. The concentrating mechanism required glucose as well as Na+, K+, and Ca++ ions in the media and is inhibited by ouabain, dinitrophenol, iodoacetate, cyanide, fluoride, desoxycorticosterone, and hydrocortisone. It demonstrates saturation kinetics with increasing concentrations of Lascorbate in the media and is competitively inhibited by D-isoascorbate. Ascorbate is secreted into the aqueous humor of the guinea pig's posterior chamber. By raising the plasma ascorbate level, saturation kinetics can be demonstrated.