Proton NMR spectroscopy of glucose consumption by cultured lens epithelial cells

Proton NMR spectroscopy was performed on media collected from cultured lens epithelial cells of the rabbit eye incubated with Krebs-Ringer's solution containing 5.5mM 13C-glucose (labeled at the C-1 position). Comparing proton resonance intensities of the lactate-methyl group of the C-3 carbon (both 12C and 13C) enabled us to quantify the hexose monophosphate shunt (HMPS) activity. Our results showed that the epithelial cells remained stable in both lactate production and HMPS activity for at least 8 hours. In addition, although tBHP (1mM) resulted in an increase of glucose flow through the HMPS, the rate of lactate production was not affected. In contrast, KCN (2mM) caused a 72% increase of lactate production and a slight (6%) decrease of glucose consumption through the HMPS.