Abstract
Gluconcogenesis, the predominant source of glucose to the fasting infant, allows only a precarious balance to be maintened with glucose utilization, as reflected by the fasting decrease of plasma glucose. This study is the first quanlification of gluconeogenesis at this age. (3-13C] lactate and [6,6-2H2] glucose tracers were infused in 12 infants aged 1-25 mo during a brief 6-16 h fast. At substrate and isotopic steady-state, glucose and lactate averaged 4.0±0.2 mM and 1.8±0.1 mM respectively, with [3-13C] lactale and [6.6-2H2] glucose enrichments at 1.9±0.2 and 2.5±0.2 mol%E. The appearance of glucose (28±3 μmol/k.min) and lactate (29±5 μmol/k.min) in bloodstream was 2-3 fold that in postabsorptive adults. The incorporation of 13C from lactate into specific carbon positions of glucose was measured using a new gas chromatography-mass spectrometry technique, which corrects for metabolic exchange of carbons in the Krebs cycle. 32±4% of the total glucose production was due to lactate gluconeogenesis, both being correlated (r=0.67, p<0.01). Gluconeogenesis was the major roule (40-90%) for lactate disposal, with a MCR of 18±2 ml/k.min).
In conclusion, laclate gluconeogenesis accounts for approximately 1/3 of the total fasting glucose production in infants, and its rate is 2.5-4 fold higher than in adults.
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Nurjhan, N., Rocchiccioli, F., Zeller, J. et al. GLUCONEOGENESIS FROM LACTATE IN FASTING INFANTS. Pediatr Res 33 (Suppl 5), S70 (1993). https://doi.org/10.1203/00006450-199305001-00401
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DOI: https://doi.org/10.1203/00006450-199305001-00401