AJP - Endocrinology and Metabolism, Vol 269, Issue 4 E774-E778, Copyright © 1995 by American Physiological Society
Glucose production in glycogen storage disease I is not associated with increased cycling through hepatic glycogen
K. I. Rother and W. F. Schwenk
Department of Pediatrics, Mayo Clinic, Rochester, Minnesota 55905, USA.
Children with glycogen storage disease type I (GSD I) lack the ability to
convert glucose 6-phosphate to glucose and yet are able to produce glucose
endogenously. To test the hypothesis that the source of this glucose is
increased cycling of glucose moieties through hepatic glycogen, six
children with GSD I were studied on two occasions during which they
received enteral glucose for 6 h at 35 or 50 mumol.kg-1.min-1 along with
[6,6-2H2]glucose to measure plasma glucose flux and [1-13C]galactose to
label intrahepatic uridyl diphosphate (UDP)-glucose. After 3 h,
acetaminophen was given to estimate UDP-glucose flux (reflecting the rate
of glycogen synthesis). Mean steady-state plasma glucose concentrations
(4.8 +/- 0.2 vs. 5.8 +/- 0.1 mM) and total flux (34.8 +/- 1.7 vs. 47.5 +/-
2.0 mumol.kg-1.min-1) were increased (P < 0.05 or better) on the
high-infusion day. Endogenous glucose production was detectable only on the
low-infusion day (2.0 +/- 0.5 mumol.kg-1.min-1). UDP-glucose flux was
increased (P < 0.05) on the high-infusion day (25.8 +/- 1.6 vs. 34.7 +/-
4.1), ruling out cycling of glucose moieties through glycogen with release
of glucose by debrancher enzyme as the source of glucose production.
