Intestinal folate absorption: <i>I. 5-Methyltetrahydrofolic acid</i>

Williamson Strum; Peter F. Nixon; Joseph B. Bertino; Henry J. Binder

doi: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: 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: 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: 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: PubMed | Google Scholar

Published in Volume 50, Issue 9 on September 1, 1971
J Clin Invest. 1971;50(9):1910–1916. https://doi.org/10.1172/JCI106683.
© 1971 The American Society for Clinical Investigation

Published September 1, 1971 - Version history

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.

Images.