Figure 3–

Deuterium label loss and kinetic isotope effect for lactate, glutamate and glutamine in rat brain following 20 min of intravenous infusion of [6,6-²H₂, 6-¹³C]-glucose and [5,6-¹³C₂]-glucose. (A) Experimental ¹³C NMR spectrum (top) for [4-¹³C]-glutamate together with the fitted contributions from non-deuterated [4-¹³C]-glutamate (red), single-deuterated [4-²H, 4-¹³C]-glutamate (blue), double-deuterated [4,4-²H₂, 4-¹³C]-glutamate (green) and non-deuterated [4, 5-¹³C₂]-glutamate (gray). The residual between the experimental and total fitted spectra is shown as the bottom trace. (B) Deuterium label loss for [3-¹³C]-lactate, [4-¹³C]-glutamate and [4-¹³C]-glutamine originating from [6,6-²H₂,6-¹³C]-glucose. Non, single and double-deuterated compounds are indicated by red, blue and green bars, respectively. For each compound the sum of the three contributions equals 100%. (C) Kinetic isotope effect for lactate, glutamate and glutamine. The absolute amounts of non, single and deuterated compounds are added together and compared to the absolute amount of [2,3-¹³C₂]-lactate or [4,5-¹³C₂]-glutamate or glutamine which is defined as 100%.