A Method for Studying Hexose Penetration into the Lens Using the Sorbitol Pathway as a Trapping Mechanism

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Abstract
Evidence is given that the rat lens can accumulate labeled galactose from a medium at low concentrations (5 x 10-5 m) and sequester it as dulcitol with such efficiency, that in 3 hr. the tracer concentration in the lens water exceeds that in the medium by over 50%. A comparison with fructose under the same conditions demonstrates the behavior of a typical sugar which accumulates more slowly. A theoretical analysis of the situation, especially with regard to the action of the sorbitol pathway on galactose, indicates that the accumulation of galactose (as dulcitol) occurs without complications due to back diffusion, concentration build-up, or metabolic degradation. The use of the sorbitol pathway to trap galactose in this manner may serve as a sensitive and easy method for the study of changes in lens membrane permeability to sugar in early cataractogenesis.