Carbon 13 NMR study of glycogen metabolism in the baboon liver in vivo

In vivo glycogen metabolism was investigated at 2 Tesla by 13C NMR in the baboon liver. Two concentric surface coils were used for 13C observation and proton decoupling, respectively. Spectra were acquired in 2 to 10 minutes with a 60 ms repetition time. After 3 hours of glucose infusion in the 48 hr fasted animal, 3 g of 99%-enriched [1-13C]glucose were injected. The distribution of the label on C-1 and also C-2, C-5 and C-6 of glycogen indicated 65% and 35% contributions of the direct and indirect pathways to glycogen synthesis from glucose, respectively. The results show that hepatic metabolic pathways and rates can be followed in vivo in large animals by 13C NMR at 2 Tesla.