Pentose Pathway in Human Liver

• Published in: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Vol. 85; no. 13; pp. 4682 - 4685
• Main Authors: Magnusson, Inger, Chandramouli, Visvanathan, Schumann, William C., Kumaran, Kozhikot, Wahren, John, Landau, Bernard R.
• Format: Journal Article Publication
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.07.1988; National Acad Sciences
• Subjects: 550201 - Biochemistry- Tracer Techniques; Acetaminophen - metabolism; Adult; ALDEHYDES; Analytical, structural and metabolic biochemistry; ANIMALS; BASIC BIOLOGICAL SCIENCES; Biological and medical sciences; BIOLOGICAL MATERIALS; BIOLOGICAL PATHWAYS; BIOLOGICAL WASTES; BLOOD; Blood glucose; BODY; BODY FLUIDS; CARBOHYDRATES; Carbon; CARBON 14 COMPOUNDS; Diflunisal - metabolism; DIGESTIVE SYSTEM; DISTRIBUTION; Female; FEMALES; Fundamental and applied biological sciences. Psychology; GLANDS; GLUCOSE; Glucose - metabolism; Glucose-6-Phosphate; Glucosephosphates - metabolism; Glucuronides; Glycogen; HEXOSES; Humans; Inactivation, Metabolic; Ingestion; LABELLED COMPOUNDS; LIVER; Liver - metabolism; Male; MALES; MAMMALS; MAN; MATERIALS; MEN; METABOLISM; MONOSACCHARIDES; ORGANIC COMPOUNDS; ORGANS; Other biological molecules; Pentose Phosphate Pathway; PENTOSES; PRIMATES; Radiocarbon; Random allocation; Ribose - metabolism; SACCHARIDES; TISSUE DISTRIBUTION; URINE; VERTEBRATES; WASTES; WOMEN; Human; Carbohydrate; Hepatocyte; Metabolism; Liver; Pentose
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.85.13.4682

[1-14C]Ribose and [2-14C]glucose were given to normal subjects along with glucose loads (1 g per kg of body weight) after administration of diflunisal and acetaminophen, drugs that are excreted in urine as glucuronides. Distributions of 14C were determined in the carbons of the excreted glucuronides and in the glucose from blood samples drawn from hepatic veins before and after glucagon administration. Eighty percent or more of the 14C from [1-14C]ribose incorporated into the glucuronic acid moiety of the glucuronides was in carbons 1 and 3, with less than 8% in carbon 2. In glucuronic acid from glucuronide excreted when [2-14C]glucose was given, 3.5-8.1% of the 14C was in carbon 1, 2.5-4.3% in carbon 3, and more than 70% in carbon 2. These distributions are in accord with the glucuronides sampling the glucose unit of the glucose 6-phosphate pool that is a component of the pentose pathway and is intermediate in glycogen formation. It is concluded that the glucuronic acid conjugates of the drugs can serve as a noninvasive means of sampling hepatic glucose 6-phosphate. In human liver, as in animal liver, the classical pentose pathway functions,not the L-type pathway, and only a small percentage of the glucose is metabolized via the pathway.