Document Detail


Food restriction stimulates conjugation of p-nitrophenol in perfused rat liver.
MedLine Citation:
PMID:  7786027     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Rates of conjugation of p-nitrophenol were studied in livers from normal and food-restricted rats perfused with either p-nitroanisole or p-nitrophenol. Female Sprague-Dawley rats had ad libitum access to a Purina 5001 nonpurified diet (control) or were given 65% of the intake of controls for 3 weeks. Livers were perfused with oxygenated Krebs-Henseleit buffer using a nonrecirculating system. Maximal rates of conjugation of p-nitrophenol, generated either from the O-demethylation of p-nitroanisole (200 microM) or from the infusion of p-nitrophenol (70 microM), were elevated significantly nearly twofold by food restriction. Thus, food restriction stimulates conjugation in the intact liver cell. Specifically, rates of conjugation were increased from 2.1 +/- 0.2 to 3.7 +/- 0.4 and from 3.3 +/- 0.6 to 5.8 +/- 0.5 mumol/g/h when 200 microM p-nitroanisole or 70 microM p-nitrophenol were infused, respectively. On the other hand, rates of conjugation were not affected by food restriction when low concentrations of p-nitroanisole (50 microM) or p-nitrophenol (20 microM) were infused. Further, food restriction did not alter rates of conjugation in isolated microsomes supplemented with excess UDPGA. Interestingly, both UDP-glucose and UDP-glucuronic acid were increased significantly in liver extracts from food-restricted rats when livers were perfused with high but not low concentrations of p-nitrophenol. Under these conditions, the increase in UDP-glucuronic acid was threefold. Moreover, food restriction increased carbohydrate release from the liver about twofold. Glycogen content was also increased significantly in liver extracts from 8.4 +/- 1.9 to 60.4 +/- 13.8 mmol/kg wet weight by food restriction. Taken together, these data support the hypothesis that food restriction stimulates conjugation of p-nitrophenol concentrations by increasing the supply of the pivotal cofactor UDP-glucuronic acid from carbohydrate reserves (e.g., glycogen).
Authors:
W Qu; F C Kauffman; R G Thurman
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Archives of biochemistry and biophysics     Volume:  319     ISSN:  0003-9861     ISO Abbreviation:  Arch. Biochem. Biophys.     Publication Date:  1995 Jun 
Date Detail:
Created Date:  1995-07-17     Completed Date:  1995-07-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372430     Medline TA:  Arch Biochem Biophys     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  451-6     Citation Subset:  IM    
Affiliation:
Department of Pharmacology, University of North Carolina at Chapel Hill 27599-7365, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Carbohydrates / analysis
Female
Food Deprivation / physiology*
Glucuronosyltransferase / analysis
Liver / metabolism*
Microsomes, Liver / metabolism
Nitrophenols / metabolism*
Perfusion
Rats
Rats, Sprague-Dawley
Uridine Diphosphate Glucuronic Acid / pharmacology
Chemical
Reg. No./Substance:
0/Carbohydrates; 0/Nitrophenols; 100-02-7/4-nitrophenol; 2616-64-0/Uridine Diphosphate Glucuronic Acid; EC 2.4.1.17/Glucuronosyltransferase

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