Quantitative Histochemistry of Retina II. ENZYMES OF GLUCOSE METABOLISM

Abstract

It was previously reported that lactic and malic dehydrogenases are distributed according to strikingly different patterns in the various layers of the retina (1). This suggested that the layers differ greatly in regard to glycolytic and oxidative capacity. In this paper will be reported the distribution of the following enzymes of glucose metabolism: hexokinase, phosphoglucoisomerase, phosphofructokinase, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and phosphoglucomutase. This permits examination of most of the enzymes leading from glucose through glucose 6-phosphate toward each of three major pathways: glycolysis, direct oxidation, and glycogen formation. The differences in distribution of certain of these enzymes are dramatic and may indicate how the retina meets some of its special problems. Comparison of the avascular retina of the rabbit with the partially vascularized retina of the monkey (Mucuca rhesus) helps in the assessment of the effects of blood supply on metabolic patterns.