Fig. 3. Upper panel: Assay of standard amounts of D-glucose, D-fructose or a mixture of the two hexoses by the glucose-6-phosphate dehydrogenase procedure; mean values (± SEM) are derived from two separate experiments for each hexose or mixture of hexoses and normalized relative to the sum of the optical densities recorded with each of the three standard amounts of hexose(s) in each experiment. Lower panel: Time course for the changes in plasma D-fructose concentration after oral administration of D-fructose (6.9 µmol/g); mean values (± SEM) refer to 4 individual experiments.