Abstract
3H-labeled alpha aminoisobutyric acid (AIB) was accumulated against a concentration gradient by rabbit ciliary body-iris preparations in vitro. The accumulation ratio tissue per medium was greater in the ciliary processes than in the iris. The process was saturable and energy and temperature dependent. Accumulation ratio was depressed by other amino acids, metabolic inhibitors, and when Na+ or K+ concentrations in the medium were lowered. Ouabain 10-7M and demecarium 3 x 10-4M reduced the ratio while echothiophate 3 x 10-3M, pilocarpine 10-2M, and acetazolamide 10-4M had very little effect. There was little difference in accumulation ratio between preparations from very young and adult animals. The rate of run-out of AIB from ciliary body-iris preparations into AIB free media decreased at low temperature but was increased by iodoacetate 3 x 10-3M, cyanide 5 x 10-3M, ouabain 3 x 10-5M, and demecarium 2 x 10-3M. Attempts to disentangle transcellular transport from cellular accumulation were not successful.