Effects of galactose on direct and indirect pathway estimates of hepatic glycogen synthesis.
Summary of "Effects of galactose on direct and indirect pathway estimates of hepatic glycogen synthesis."
Hepatic glycogen is formed by direct and indirect pathways whose activities reflect altered nutrition or disease. Direct/indirect pathway measurements often involve test meals where ~10% of carbohydrate is galactose, but its effects on direct/indirect pathway estimates are unknown. Therefore, direct/indirect pathway contributions in 24-hr fasted rats given 2g/kg 100% glucose (GLU, n=6) or 90% glucose-10% galactose (GLU+GAL, n=6) were measured by [U-13C]glucose dilution and by position-5/position-2 glycogen enrichment (H5/H2) from 2H2O. For GLU+GAL, galactose glycogenesis was independently measured with [1-13C]galactose. Glycogenesis was equivalent in both groups but for GLU+GAL, 23+/-4% of glycogen was derived from galactose. [U-13C]glucose reported a 30+/-3% direct pathway contribution to glycogenesis for GLU but only 20+/-3% for GLU+GAL (p=0.012 vs. GLU). H5/H2 yielded identical direct pathway estimates (32+/-3% GLU, 29+/-6% GLU+GAL). Thus, galactose glycogenesis was undetected by H5/H2 while [U-13C]glucose reported a reduced direct/indirect pathway ratio. With [1-13C]galactose also present, correct glycogenic source contributions were obtained.
Affiliation
Department of Life Sciences and Center for Neurosciences and Cell Biology, University of Coimbra, Rua dos Estudos, Apartado 3126, 3001-401 Coimbra, Portugal; Laboratory of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra, Azinhaga de
Journal Details
This article was published in the following journal.
Name: Metabolic engineering
ISSN: 1096-7184
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20797446
- DOI: http://dx.doi.org/10.1016/j.ymben.2010.08.002
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