Abstract
The entry of 3H-cycloleucine from blood into the anterior chamber and the rate of aqueous humor formation ivere studied in vervet monkeys. 3H-cycloleucine was given parenterally. The anterior chamber was perfused with a buffer solution containing 131I-albumin or 14-Cinulin. The rate of aqueous humor formation was calculated from the dilution.The rate of entry of 3H-cycloleucine was estimated from the concentration in the perfusate. A rise in intraocular pressure of 10 and 20 cm. of water reduced the concentration of cycloleucine in the anterior chamber perfusate by 25 and 32 per cent, respectively; the corresponding effect on the rate of aqueous humor formation was an average reduction by 0.05 and 0.04 µL per minute per millimeter of Hg, respectively. Acetazolamide 10 and 100 mg. per kilogram of body weight intravenously reduced the concentration of 3H-cycloleucine in the perfusate by 10 and 26 per cent, respectively, and the rate of formation by 30 and 80 per cent, respectively. Pilocarpine (1O-4M) in the infusion fluid reduced the concentration of 3H-cycloleucine in the perfusate by 21 per cent and the rate of formation on an average by 1.1 µL per minute. These effects were abolished by atropine (3 x 10-5M). Norepinephrine (6 x 10-5M) reduced the concentration of cycloleucine in the perfusate by 29 per cent but tended to stimulate the rate of aqueous humor formation. Norepinephrine (3 x 10-4M) had similar effects. A rise in intraocular pressure and acetazolamide 100 mg. per kilogram had similar effects on the rate of entry of 14C-AIB and 3H-cycloleucine. It was concluded that the reduced rate of entry of 3H-cycloleucine, observed after a rise in intraocular pressure, acetazolamide, and pilocarpine, was likely to be due to a reduced rate of aqueous humor -flow from the posterior into the anterior chamber, whereas the effect of norepinephrine was due to reduced diffusion of 3H-cycloleucine mainly across the anterior surfaceof the iris.