Localized proton NMR observation of [3‐¹³C] lactate in stroke after [1‐¹³C] glucose infusion

To assess whether elevated lactate in stable stroke is being actively produced from blood glucose localized ¹H NMR stimulated echo spectra were obtained from a patient in the region of a 32‐day‐old cortical infarct before and 60–100 min after infusion of [1‐¹³C]glucose. Prior to the infusion the spectrum from the region of the infarct contained an elevated resonance from C3 lactate and a greatly reduced resonance from N‐acetyl groups relative to an unaffected contralateral region. After the infusion two additional resonances were observed at 62 and −64 Hz relative to the unlabeled resonance of C3 lactate which were assigned on the basis of chemical shift and relative intensity to[3‐¹³C]lactate. The [3‐¹³C]lactate fractional enrichment in the infarct region was measured to be 32% which is within error one‐half the average [1‐¹³C]plasma glucose enrichment during the postinfusion NMR measurement. The result suggests that the stroke lactate pool was completely derived from infused glucose. © 1991 Academic Press, Inc.