In vivo measurement of gluconeogenesis in animals and humans with deuterated water: A simplified method

The contribution of gluconeogenesis to glucose production can be measured b y comparing after ingestion of deuterated water the enrichment in deuterium of the hydrogen bound to carbon 5 of glucose with that of hydrogen bound t o carbon 2 or with the deuterium enrichment of plasma water. The method dev eloped by Landau ei al. for measuring deuterium enrichment on carbon 5 by g as chromatography-mass spectrometry analysis is tedious and time consuming. We developed a simpler procedure for measuring this deuterium enrichment D euterium enrichment on carbons 5 and 6 of glucose is measured using the 1,2 -5,6-diisopropylidene-3-0-acetyl-a-furanosyl derivative. Enrichment in posi tion 6 is measured using the hexamethylenetetramine procedure and substract ed from the enrichment on carbons 5 and 6 to obtain the specific enrichment on carbon 5. We tested first this method in post-absorptive and fasted rat s (plasma water enrichment 0.6%) infused simultaneously with [6,6-H-2(2)] g lucose in order to obtain not only the percent contribution of gluconeogene sis, but also glucose turnover rate and absolute gluconeogenesis flux. In p ost-absorptive and starved rats gluconeogenesis represented respectively 46 .7+/-2.0% and 94.1+/-2.0% of glucose production and a flux of 31.1+/-1.8 an d 38.9+/-0.9 mu mol/kg/min. The method was then used in humans. The contrib ution in the post-absorptive state of gluconeogenesis to glucose appearance measured in control and type 2 diabetic subjects (plasma water enrichment 0.23-0.38%) was 40.7+/-5.0% and 65.7+/-3.3% (p < 0.05) respectively. In con clusion this simplified method appears useful for in vivo studies of glucon eogenenis.