Dynamic assessment of hexose monophosphate shunt activity in the intact rabbit lens by proton NMR spectroscopy.

A proton nuclear magnetic resonance technique is demonstrated for ascertaining the real-time contribution of the hexose monophosphate shunt to glucose metabolism in the intact incubated rabbit lens. This measurement requires incubation of the tissue in medium supplemented with [1-13C]glucose, and depends on the presence of the 13C label in the methyl position of lactate which creates satellite resonances by way of 13C - 1H spin-spin scalar coupling. The assumptions required to make the measurement are presented. For lenses maintained under control conditions, a basal level corresponding to 5% hexose monophosphate shunt activity was determined. An eight-fold increase in activity was observed under conditions known to stimulate the shunt.