Document Detail


Absorption of D- and L-carnitine by the intestine and kidney tubule in the rat.
MedLine Citation:
PMID:  6722145     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The process by which L- and D-carnitine are absorbed was investigated using the live rat and the isolated vascularly perfused intestine. A lumenal dose of 2-6 nmol in the perfused intestine resulted in less than 5% transport of either isomer to the perfusate in 30 min. The L-isomer was taken up by the intestinal tissue about twice as rapidly as the D-isomer by both the perfused intestine (52.8% and 21.6%, respectively) and the live animal (80% and 50%, respectively) in 30 min. After 1 h 90% of the L-carnitine had accumulated in the intestinal tissue and was released to the circulation over the next several hours. Accumulation of D-carnitine reached a maximum of 80% in 2 h and release to the circulations was similar to that of L-carnitine. Uptake of both L-[14C]carnitine and acetyl-L-[14C]carnitine was more rapid in the upper jejunal segment than in other portions of the small intestine. Acetylation occurred in all segments, resulting in nearly 50% conversion to this derivative in 5 min. Increasing the dose of L-carnitine reduced the percent acetylation. The uptake of both isomers was a saturable process and high concentrations of D-carnitine, acetyl-L-carnitine and trimethylaminobutyrate inhibited L-carnitine uptake. In the live animal after 5 h, the distribution of isotope from L-[14C]carnitine and D-[3H]carnitine differed primarily in the muscle where 29.5% of the L-carnitine and 5.3% of the D-carnitine was found and in the urine where 2.9% of the L-carnitine and 7.1% of the D-carnitine was found. The renal threshold for L-carnitine was 80 microM and for D-carnitine 30 microM, in the isolated perfused kidney. Approx. 40% of the L-carnitine but none of the D-carnitine excreted in the urine was acetylated. L-Carnitine and D-carnitine competed for tubular reabsorption.
Authors:
C J Gross; L M Henderson
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  772     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  1984 May 
Date Detail:
Created Date:  1984-07-09     Completed Date:  1984-07-09     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  209-19     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Acetylation
Animals
Biological Transport
Carbon Radioisotopes / diagnostic use
Carnitine / metabolism*
Duodenum / metabolism
Ileum / metabolism
Intestinal Absorption*
Jejunum / metabolism
Kidney Tubules / metabolism*
Kinetics
Male
Rats
Rats, Inbred Strains
Stereoisomerism
Tissue Distribution
Grant Support
ID/Acronym/Agency:
AM 19764/AM/NIADDK NIH HHS
Chemical
Reg. No./Substance:
0/Carbon Radioisotopes; 541-15-1/Carnitine

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


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