AJP - Endocrinology and Metabolism, Vol 259, Issue 5 E757-E762, Copyright © 1990 by American Physiological Society

ARTICLES

Interpretation of isotopomer patterns in tracing glycogen synthesis and glucose recycling using [13C6]glucose

C. Des Rosiers, B. R. Landau and H. Brunengraber
Department of Nutrition, University of Montreal, Quebec, Canada.

Tracing glycogen synthesis with [U-13C]glucose involves determination of isotopomer patterns in precursors and products. The contribution of the direct pathway to glycogen synthesis has been estimated from the ratio (R) of the number of glycogen glucose molecules having six 13C atoms to the total number of glucose molecules having one to six 13C atoms. Using theoretical examples, we show that the equation to calculate R underestimates the contribution of the direct pathway. We derive a correct stoichiometric expression for R. Also, we show how to correct these estimates for 1) recondensation of two M+3 three-carbon intermediates into M+6 glucose 6-phosphate, and 2) the increasing enrichment of arterial glucose in various isotopomers arising from the indirect pathway. Finally, using the developed formulas we recalculate data from the literature. Similar considerations apply to investigations of glucose recycling using [U-13C6]glucose.

This article has been cited by other articles:

				J. Katz and J. A. Tayek Recycling of glucose and determination of the Cori Cycle and gluconeogenesis Am J Physiol Endocrinol Metab, September 1, 1999; 277(3): E401 - E407. [Abstract] [Full Text] [PDF]

				B. R. Landau Limitations in the use of [U-13C6]glucose to estimate gluconeogenesis Am J Physiol Endocrinol Metab, September 1, 1999; 277(3): E408 - E413. [Full Text] [PDF]