Biomaterial Database

Recycling of glucose and determination of the Cori Cycle and gluconeogenesis. 1999

J Katz, and J A Tayek

Department of Internal Medicine, Harbor-University of California Los Angeles Medical Center, Torrance, California 90502, USA.

We have derived equations, by employing [U-(13)C]glucose and mass isotopomer analysis, to determine the pathways of glycogen synthesis (J. Katz, W. P. Lee, P. A. Wals, and E. A. Bergner. J. Biol. Chem. 264: 12994-13004, 1989). More recently, by use of these methods we have derived equations to determine the rate of glucose recycling and of gluconeogenesis [Tayek and Katz. Am. J. Physiol. 270 (Endocrinol. Metab. 33): E709-E717, 1996 and 272 (Endocrinol. Metab. 35): E476-E484, 1997, and Katz and Tayek. Am. J. Physiol. 275 (Endocrinol. Metab. 38): E537-E542, 1988]. The former equations have been criticized and challenged by C. Des Rosiers, B. R. Landau, and H. Brunengraber [Am. J. Physiol. 259 (Endocrinol. Metab. 22): E757-E762, 1990], and the latter recently by B. R. Landau, J. Wahren, S. F. Previs, G. K. Ekberg, D. Yang, and H. Brunengraber [Am. J. Physiol. 274 (Endocrinol. Metab. 37): E954-E961, 1998]. Landau et al. claimed that our equations were in error and "corrected" them. Their analysis, and their values for recycling and gluconeogenesis (GNG) differ markedly from ours. We show here our equations and estimates of recycling and GNG to be correct. We present here a theoretical analysis of recycling and discuss the determination of the Cori Cycle and GNG. We illustrate by numerical examples the difference in parameters of glucose metabolism calculated by the methods of Katz and Landau. J. Radziuk and W. N. P. Lee [Am. J. Physiol. 277 (Endocrinol Metab. 40): E199-E207, 1999] and J. K. Kelleher [Am. J. Physiol. 277 (Endocrinol. Metab. 40): E395-E400, 1999] present a mathematical analysis that, although differing in some respects from Landau's, supports his equation for GNG. We show in the APPENDIX that their derivation of the equation for GNG is incorrect.

UI	MeSH Term	Description	Entries
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D001786	Blood Glucose	Glucose in blood.	Blood Sugar,Glucose, Blood,Sugar, Blood
D005943	Gluconeogenesis	Biosynthesis of GLUCOSE from nonhexose or non-carbohydrate precursors, such as LACTATE; PYRUVATE; ALANINE; and GLYCEROL.
D005947	Glucose	A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.	Dextrose,Anhydrous Dextrose,D-Glucose,Glucose Monohydrate,Glucose, (DL)-Isomer,Glucose, (alpha-D)-Isomer,Glucose, (beta-D)-Isomer,D Glucose,Dextrose, Anhydrous,Monohydrate, Glucose
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia