Effect of Insulin on Pathways of Glucose Oxidation in the Rat Lens

Abstract

EXPERIMENTAL evidence as to whether lens is a tissue which responds to insulin has been inconclusive. Some investigators have found that glucose uptake by the isolated intact lens is increased after administration of insulin in vivo^1,2. However, neither a direct effect in vitro on glucose uptake could be demonstrated^1,3, nor did insulin influence the accumulation of labelled glucose by the intact lens⁴. Recent work in this laboratory has shown that insulin causes a small but consistent increase of glucose uptake by the intact lens in Krebs–Ringer bicarbonate medium⁵. Kinoshita and Wachtl⁶ have found that lens is capable of metabolizing glucose by both the Embden–Meyerhof pathway and the hexose monophosphate shunt. This communication deals with the effect of insulin on the two oxidative pathways in the rat lens and demonstrates an alteration of glucose oxidation in lenses of diabetic rats.