P-31-NUCLEAR MAGNETIC-RESONANCE EVIDENCE OF AN ACTIVATED HEXOSE-MONOPHOSPHATE SHUNT IN HYPERGLYCEMIC RAT LENSES IN-VIVO

Using P-31-nuclear magnetic resonance spectroscopy, we have identified elevated concentrations of sedoheptulose-7-phosphate (S-7-P) in lense s from three animal models of hyperglycemia: streptozotocin-induced di abetic rats, galactose-fed rats, and xylose-fed rats. This observation provides a unique and independent confirmation of the activation of t he hexose monophosphate shunt (HMPS) pathway in the hyperglycemic lens in vivo. While the elevation in concentration of S-7-P was very drama tic, the other HMPS metabolites in these tissues were below the thresh old of detection, as expected for the HMPS pathway near equilibrium. i n terms of nonenzymatic glycation, these results suggest that the only HMPS metabolite of importance in the hyperglycemic rat lens is S-7-P. Although in the diabetic lens its role appears to be relatively minor , in the galactosemic lens this compound may be an important contribut or to the increased production of advanced glycosylation end products.