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Free access | 10.1172/JCI106683
Department of Internal Medicine, Yale University, New Haven, Connecticut 06510
Department of Pharmacology, Yale University, New Haven, Connecticut 06510
Find articles by Strum, W. in: JCI | PubMed | Google Scholar
Department of Internal Medicine, Yale University, New Haven, Connecticut 06510
Department of Pharmacology, Yale University, New Haven, Connecticut 06510
Find articles by Nixon, P. in: JCI | PubMed | Google Scholar
Department of Internal Medicine, Yale University, New Haven, Connecticut 06510
Department of Pharmacology, Yale University, New Haven, Connecticut 06510
Find articles by Bertino, J. in: JCI | PubMed | Google Scholar
Department of Internal Medicine, Yale University, New Haven, Connecticut 06510
Department of Pharmacology, Yale University, New Haven, Connecticut 06510
Find articles by Binder, H. in: JCI | PubMed | Google Scholar
Published September 1, 1971 - More info
Intestinal absorption of the monoglutamate form of the principal dietary and circulating folate compound, 5-methyltetrahydrofolic acid (5-MTHF), was studied in the rat utilizing a synthetic highly purified radiolabeled diastereoisomer. Chromatography confirmed that the compound was not altered after transfer from the mucosa to the serosa. Accumulation against a concentration gradient was not observed in duodenal, jejunal, or ileal segments at 5-MTHF concentration from 0.5 to 500 nmoles/liter. Unidirectional transmural flux determination also did not indicate a significant net flux. Mucosal to serosal transfer of 5-MTHF was similar in all segments of the intestine and increased in a linear fashion with increased initial mucosal concentrations. Further, no alteration in 5-MTHF transfer was found when studied in the presence of metabolic inhibitors or folate compounds.
These results indicate that 5-MTHF is not absorbed by the rat small intestine by a carrier-mediated system and suggest that 5-MTHF transfer most likely represents diffusion.
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