Sorbitol Pathway in Lenses of Normal Diabetic Rabbits

Abstract

The concentrations of sugars, D-glucose, D-sorbitol, D-fructose and myo-inositol, and the activities of enzymes, aldose reductase and sorbitol dehydrogenase, which are associated with the sorbitol pathway, in the lenses of normal and alloxan-diabetic rabbits were determined. It has been demonstrated that the formation of sorbitol and fructose is accelerated and the level of myo-inositol is decreaed in diabetic rabbit lens. The concentrations of glucose, sorbitol, fructose and myo-inositol in normal rabbit lens were about 0.23, 6.5, 0.3 and 6.0μmol/g wet weight of lens, and those in diabetic rabbit lens were about 0.45, 29, 3 and 0.24μmol/g wet weight of lens, respectively. It has been suggested that the levels of aldose reductase and sorbitol dehydrogenase activities in whole lens are unaffected by diabetic conditions. However, we found that the distribution pattern in the lens of aldose reductase was different under normal and diabetic conditions. In the diabetic condition, the level of the enzyme in the outer zone including the capsule, epithelium and cortex, increased, and that in the nucleus decreased.