HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 275, Issue 47, 36787-36793, November 24, 2000

This Article Full Text Full Text (PDF) All Versions of this Article: 275/47/36787    most recent M004739200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kurland, I. J. Articles by Lee, W.-N. P. Search for Related Content PubMed PubMed Citation Articles by Kurland, I. J. Articles by Lee, W.-N. P. Social Bookmarking                      What's this?

Loss of [¹³C]Glycerol Carbon via the Pentose Cycle
IMPLICATIONS FOR GLUCONEOGENESIS MEASUREMENT BY MASS ISOTOPER DISTRIBUTION ANALYSIS^*

Irwin J. Kurland^§¶, Allison Alcivar^§, Sara Bassilian, and Wai-Nang P. Lee

From the  Molecular Biology Institute and ^§ Department of Medicine, Division of Endocrinology, Diabetes and Metabolism Signaling Laboratory, UCLA, Los Angeles, California 90024 and the  Department of Pediatrics, Harbor-UCLA Medical Center, Torrance, California 90502

Whereas many reports substantiated the suitability of using [2-¹³C]glycerol and Mass Isotoper Distribution Analysis for gluconeogenesis, the use of [¹³C]glycerol had been shown to give lower estimates of gluconeogenesis (GNG). The reason for the underestimation has been attributed to asymmetric isotope incorporation during gluconeogenesis as well as zonation of gluconeogenic enzymes and a [¹³C]glycerol gradient across the liver. Since the cycling of glycerol carbons through the pentose cycle pathways can introduce asymmetry in glucose labeling pattern and tracer dilution, we present here a study of the role of the pentose cycle in gluconeogenesis in Fao cells. The metabolic regulation of glucose release and gluconeogenesis by insulin was also studied. Serum-starved cells were incubated for 24 h in Dulbecco's modified Eagle's media containing 1.5 mM [U-¹³C]glycerol. Mass isotopomers of whole glucose from medium or glycogen and those of the C-1C-4 fragment were highly asymmetrical, typical of that resulting from the cycling of glucose carbon through the pentose cycle. Substantial exchange of tracer between hexose and pentose intermediates was observed. Our results offer an alternative mechanism for the asymmetrical labeling of glucose carbon from triose phosphate. The scrambling of ¹³C in hexose phosphate via the pentose phosphate cycle prior to glucose release into the medium is indistinguishable from dilution of labeled glucose by glycogen using MIDA and probably accounts for the underestimation of GNG using ¹³C tracer methods.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				T. H. van Dijk, F. H. van der Sluijs, C. H. Wiegman, J. F. W. Baller, L. A. Gustafson, H.-J. Burger, A. W. Herling, F. Kuipers, A. J. Meijer, and D.-J. Reijngoud Acute Inhibition of Hepatic Glucose-6-phosphatase Does Not Affect Gluconeogenesis but Directs Gluconeogenic Flux toward Glycogen in Fasted Rats. A PHARMACOLOGICAL STUDY WITH THE CHLOROGENIC ACID DERIVATIVE S4048 J. Biol. Chem., July 6, 2001; 276(28): 25727 - 25735. [Abstract] [Full Text] [PDF]