Document Detail


Selective composition of biliary phosphatidylcholines is affected by secretion rate but not by bile acid hydrophobicity.
MedLine Citation:
PMID:  8263408     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Little is known about the mechanisms of: 1) biliary phosphatidylcholine (PC) secretion by the hepatocyte, 2) selectivity for biliary 1-palmitoyl-2-linoleoyl-PC (PLPC) secretion, and 3) exclusion of 1-stearoyl-2-arachidonyl-PC (SAPC) from bile. The experiments were designed to determine, in rats, whether selectivity (for PLPC and against SAPC) is influenced by bile acid hydrophobicity or secretion rate. We examined the effects of bile acid depletion and of ileal infusion of taurocholic acid, tauroursodeoxycholic acid, and taurochenodeoxycholic acid. Compared to bile acid depletion, infusion of each bile acid caused PLPC to decrease from 59% of bile PC to 48%, and SAPC to increase from 2.6% to 5%. Bile acid hydrophobicity had no effect on PC selectivity, but selectivity decreased to a moderate degree as total PC secretion increased. To determine whether selectivity is for preformed molecular species, we used a new method to isotopically label four species of hepatic PC. This was done by intravenous injection of PLPC and SAPC labeled in the linoleate (14C) and arachidonate (3H) moieties. Assuming rapid mixing of each PC species in the hepatocyte as supported by the specific activity data, bile SAPC and SLPC were derived entirely from hepatic preformed SAPC and SLPC; bile PLPC was from both preformed PLPC (55%) and an unlabeled input (45%, probably direct secretion of newly synthesized PLPC). In conclusion, the selective composition of bile PC is not related to bile acid hydrophobicity, but is partially lost as secretion increases within the physiologic range.
Authors:
R D Shamburek; C C Schwartz
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of lipid research     Volume:  34     ISSN:  0022-2275     ISO Abbreviation:  J. Lipid Res.     Publication Date:  1993 Nov 
Date Detail:
Created Date:  1994-01-25     Completed Date:  1994-01-25     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0376606     Medline TA:  J Lipid Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1833-42     Citation Subset:  IM    
Affiliation:
Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298.
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MeSH Terms
Descriptor/Qualifier:
Animals
Bile / secretion*
Bile Acids and Salts / administration & dosage,  chemistry,  pharmacology*
Chemistry, Physical
Ileum / drug effects
Liver / metabolism
Male
Phosphatidylcholines / analysis,  chemistry,  secretion*
Physicochemical Phenomena
Rats
Rats, Sprague-Dawley
Taurochenodeoxycholic Acid / administration & dosage,  pharmacology
Taurocholic Acid / administration & dosage,  pharmacology
Grant Support
ID/Acronym/Agency:
AM25920/AM/NIADDK NIH HHS; P01-DK38030/DK/NIDDK NIH HHS; T32-DK07150/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Bile Acids and Salts; 0/Phosphatidylcholines; 14605-22-2/tauroursodeoxycholic acid; 18892-74-5/1-stearoyl-2-arachidonylphosphatidylcholine; 516-35-8/Taurochenodeoxycholic Acid; 6931-84-6/1-palmitoyl-2-linoleoylphosphatidylcholine; 81-24-3/Taurocholic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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