title: Metabolism of [2-14C]acetate and its use in assessing hepatic Krebs cycle activity and gluconeogenesis.
abstract: To examine the fate of the carbons of acetate and to evaluate the usefulness of labeled acetate in assessing intrahepatic metabolic processes during gluconeogenesis, [2-14C]acetate, [2-14C]ethanol, and [1-14C]ethanol were infused into normal subjects fasted 60 h and given phenyl acetate. Distributions of 14C in the carbons of blood glucose and glutamate from urinary phenylacetylglutamine were determined. With [2-14C]acetate and [2-14C]ethanol, carbon 1 of glucose had about twice as much 14C as carbon 3. Carbon 2 of glutamate had about twice as much 14C as carbon 1 and one-half to one-third as much as carbon 4. There was only a small amount in carbon 5. These distributions are incompatible with the metabolism of [2-14C]acetate being primarily in liver. Therefore, [2-14C]acetate cannot be used to study Krebs cycle metabolism in liver and in relationship to gluconeogenesis, as has been done. The distributions can be explained by: (a) fixation of 14CO2 from [2-14C]acetate in the formation of the 14C-labeled glucose and glutamate in liver and (b) the formation of 14C-labeled glutamate in a second site, proposed to be muscle. [1,3-14C]Acetone formation from the [2-14C]acetate does not contribute to the distributions, as evidenced by the absence of 14C in carbons 2-4 of glutamate after [1-14C]ethanol administration.
authors.affiliation: Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.
authors.forename: W C
authors.initials: WC
authors.lastname: Schumann
authors.forename: I
authors.initials: I
authors.lastname: Magnusson
authors.forename: V
authors.initials: V
authors.lastname: Chandramouli
authors.forename: K
authors.initials: K
authors.lastname: Kumaran
authors.forename: J
authors.initials: J
authors.lastname: Wahren
authors.forename: B R
authors.initials: BR
authors.lastname: Landau
mesh_terms: D000085:Acetates / Q000378:metabolism*; D000328:Adult; D002250:Carbon Radioisotopes; D002952:Citric Acid Cycle; D000431:Ethanol / Q000378:metabolism; D005260:Female; D005943:Gluconeogenesis; D005947:Glucose / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000378:metabolism*; D008954:Models, Biological; D011865:Radioisotope Dilution Technique; D012016:Reference Values; D014508:Urea / Q000378:metabolism
chemical_list: D000085:Acetates; D002250:Carbon Radioisotopes; D000431:Ethanol; D014508:Urea; D005947:Glucose