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Abstract
14C myo-inositol was actively transported into rabbit crystalline lenses incubated in Tyrode's medium. The lens/media accumulation ratios of 14C myo-inositol reached values of 10 to 12 after 24 hr., in vitro incubations. The active transport of 14C myo-inositol into the lens was markedly decreased by metabolic inhibitors of glycolysis and oxidative phosphorylation, and by ouabain, or by an absence of Na+ ions in the incubation media. Kinetic studies revealed a Km of 0.07 mM. per liter for myo-inositol transport into lens. The efflux of 14C myo-inositol from preloaded lenses was slow, but it increased by iodoacetate. Gas chromatography determinations of myo-inositol in the lens and intraocular fluids were as follows (averages in mM. per kilogram of water): lens, 8835; anterior chamber aqueous humor, 135.1; posterior chamber aqueous humor, 93.2; vitreous humor, 235.5; and serum, 40.9. The studies support the concept of active transport and slow efflux of myo-inositol into the lens, as well as the presence of transport mechanisms specific for cyclic alcohols in tissues.