Glycolytic oscillation and effect of metabolic inhibitor on rat lens

Abnormalities in glucose metabolism are thought to be among the main causes of cataract formation. We have taken noninvasive biochemical measurements of the lens which provides us with information concerning glucose metabolism in the lens epithelium. The autofluorescence of reduced pyridine nucleotides (PN) and oxidized flavoproteins (Fp) in the rat lens epithelium was measured noninvasively as a function of time using redox fluorometry. The oscillations of the metabolic ratio, PN/Fp, were measured in vivo, in situ, and in the organ-cultured lens. The PN/Fp ratio in the organ-cultured lens ranged from 1.05 to 2.57 within a period of 60-90 minutes (mean +/- SD = 1.52 +/- 0.36). This PN/Fp ratio increased by 23% when a respiratory inhibitor (8 mM KCN) was applied to the lens. However, it decreased by 10% in the presence of a complete metabolic inhibitor (8 mM iodoacetamide). The presence of metabolic oscillations in the in vivo, in situ and cultured lens indicates that this oscillation is a local phenomenon. In cell-free extract systems, oscillations of several intermediates in the glycolytic pathway have been previously demonstrated and this PN/Fp oscillation is thought to be a reflection of glycolytic oscillation.