Energy metabolism in the lens during development of galactose cataract in rats

¹ Department of Anatomy, The University of Michigan Medical School Ann Arbor, Mich.

When young rats are fed a diet containing 50 per cent galactose, the beginning of cataract development is detected as a vacuolization of the equatorial cortex on the second day. By this time the rates of glycolysis and respiration in the lens are decreased one third below the control levels, and the lactic acid concentration in the lens water is lowered to the range found in the surrounding fluids of the eye. The corresponding barely detectable decrease in the total ATP content of the lens is interpreted to be the result of the inhibition of carbohydrate metabolism affecting only the small fraction of lenticular ATP in active turnover. Further vacuolization and subsequent opacification of the lens does not markedly change the rate of energy production but is accompanied by the disappearance of 75 per cent of the ATP. This fraction probably is located in the deeper cortex and nucleus and presumably is in less active metabolic exchange. It may escape from the lens fibers during the progressive destruction of the fiber membranes as the effect rather than cause of cataractous changes