Quantifying gluconeogenesis during fasting.
Chandramouli, Visvanathan, Karin Ekberg, William C. Schumann, Satish
C. Kalhan, John Wahren, and Bernard R. Landau.
Departments of Medicine, Biochemistry and Pediatrics, Case Western
Reserve University, Cleveland, Ohio, and Division of Clinical
Physiology, Karolinska Hospital, Stockholm, Sweden
APStracts 4:0195E, 1997.
2H2OOs use in estimating gluconeogenesis contribution to glucose
production (%GNG) was examined during progressive fasting in three
groups of healthy subjects. One group (n=3) ingested 2H2O to a body
water enrichment of [angstrom]a0.35 % 5 h into the fast. %GNG was
determined at 2 h intervals from the ratio of the enrichments of the
hydrogens at carbons 5 and 2 of blood glucose, assayed in
hexamethylenetetramine. %GNG increased from 40 +/- 8 % at 10 h to 93
+/- 6 % at 42 h. Another group ingested 2H2O over 2 1/4 h beginning
at 11 h (n=7) and 19 h (n=7) to achieve [angstrom]a0.5 % water
enrichment. Enrichment in plasma water and at carbon 2 reached steady
state [angstrom]a1 h after completing 2H2O ingestion. The
carbon5/carbon2 ratio reached steady state by the completion of 2H2O
ingestion. %GNG was 54 +/- 2 % at 14 h and 64 +/- 2 % at 22 h. A 3 h
(6,6-2H2)glucose infusion was also begun to estimate glucose
production from enrichments at carbon6, again in
hexamethylenetetramine. Glucose produced by gluconeogenesis was 0.99
+/- 0.06 mg/kg/min at both 14 h and 22 h. In a third group (n=3) %GNG
reached steady state [angstrom]a2 h after 2H2O ingestion to only
[angstrom]a0.25 % enrichment. Conclusion: %GNG by 2 h after 2H2O
ingestion and glucose production using (6,6-2H2)glucose infusion,
begun together, can be determined from hydrogen enrichments at blood
glucose carbons 2, 5 and 6. %GNG increases gradually from the
postabsorptive state to 42 h of fasting, without apparent change in
the quantity of glucose produced by gluconeogenesis at 14 h and 22 h.
Received 19 February 1997; accepted in final form 4 September
1997.
APS Manuscript Number E76-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 7 October 1997