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V. EVERETT KINSEY, D. V. N. REDDY; Studies on the Crystalline Lens XI. The relative role of the Epithelium and Capsule in Transport. Invest. Ophthalmol. Vis. Sci. 1965;4(1):104-116.
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Measurements were made of the uptake of 42K, 14C-labeled α-amino isobutyric acid (α-AIB), 22Na, 36Cl, and tritiated water (HTO) in cultured rabbit lenses and the effect of ouabain or iodoacetate on transport. Ouabain significantly decreases the uptake of 42K, whereas it increases the accumulation of 22Na; it also decreases the uptake of 14C-α-AIB, and increases that of 36Cl, but only after a time delay. The effect of iodoacetate in reducing the uptake of 14C-α-AIB is immediate. The turnover of water between the lens and its environment is extremely rapid (t½ = 15 minutes); its movement is not appreciably altered by ouabain. The relative rate of appearance of 42K and 22Na in the medium from lenses which had accumulated these isotopes, as well as the effect of ouabain, is opposite in direction to that observed for influx of the same ions. Removal of surface membranes alters both the rate of accumulation and exit of all ions in a manner similar to that of the metabolic poisons. Penetration of 42K, 14C-α-AIB, and 86Rb is greater across the anterior than posterior surface, a difference which is abolished by metabolic poisons, the removal of capsule and epithelium, and, in the case of α-AIB, by the addition of nonlabeled amino acid, to the medium. Penetration of 22Na and 36Cl is greater from the posterior side, and removal of the capsule and epithelium increases influx across both surfaces, as does iodoacetate and ouabain for 22Na but not for 36Cl. Decapsulation abolishes the effect of inhibitors. 14C-urea and HTO accumulate at equal rates across both front and back surfaces. It is concluded that potassium, α-AIB, and rubidium are actively transported into and sodium out of the lens by carrier systems located in the epithelium, and that movement of water, chloride, and urea between lens and its environment occurs passively through diffusional exchange.
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