Rapid postabsorptive metabolism of nicotinic acid in rat small intestine may affect transport by metabolic trapping

verfasst von: J. Stein, H. Daniel, E. Whang, U. Wenzel, A. Hahn, G. Rehner
Abstract: Postabsorptive metabolism of [³H]nicotinic acid by rat proximal jejunum was studied in vitro using the everted sac technique and in vivo by applying ligated loops. Metabolites were analyzed by HPLC with radiochemical detection. Within 60 min of incubation nicotinic acid was almost completely metabolized in vivo. Only 3.2% of the label could be detected in the original substrate nicotinic acid, whereas >90% of the radioactivity present in the gut wall was nicotinamide. Further in vitro experiments revealed that conversion was rapid; after 10 min of incubation >40% of the substrate was converted to other metabolites. From analysis of the serosal fluid, it was evident that only nicotinic acid and nicotinamide were transferred to the serosal compartment. Rapid conversion of nicotinic acid might affect the transport step itself by metabolic trapping, resulting in the maintenance of a substrate gradient necessary for passive absorption. In contrast, as examined by gradient centrifugation, the substrate in subcellular organelles is transferred only to a minor extent.
Externe Organisation(en): Goethe-Universität Frankfurt am Main
Typ: Artikel
Journal: Journal of Nutrition
Band: 124
Seiten: 61-66
Anzahl der Seiten: 6
ISSN: 0022-3166
Publikationsdatum: 1994
Publikationsstatus: Veröffentlicht
Peer-reviewed: Ja
ASJC Scopus Sachgebiete: Medizin (sonstige), Ernährung und Diätetik
Elektronische Version(en): https://doi.org/10.1093/jn/124.1.61 (Zugang: Offen)

BibTeX

@article{962010b2b9e34c049bcbbe29819c004b,
title = "Rapid postabsorptive metabolism of nicotinic acid in rat small intestine may affect transport by metabolic trapping",
abstract = "Postabsorptive metabolism of [3H]nicotinic acid by rat proximal jejunum was studied in vitro using the everted sac technique and in vivo by applying ligated loops. Metabolites were analyzed by HPLC with radiochemical detection. Within 60 min of incubation nicotinic acid was almost completely metabolized in vivo. Only 3.2% of the label could be detected in the original substrate nicotinic acid, whereas >90% of the radioactivity present in the gut wall was nicotinamide. Further in vitro experiments revealed that conversion was rapid; after 10 min of incubation >40% of the substrate was converted to other metabolites. From analysis of the serosal fluid, it was evident that only nicotinic acid and nicotinamide were transferred to the serosal compartment. Rapid conversion of nicotinic acid might affect the transport step itself by metabolic trapping, resulting in the maintenance of a substrate gradient necessary for passive absorption. In contrast, as examined by gradient centrifugation, the substrate in subcellular organelles is transferred only to a minor extent.",
author = "J. Stein and H. Daniel and E. Whang and U. Wenzel and A. Hahn and G. Rehner",
year = "1994",
doi = "10.1093/jn/124.1.61",
language = "English",
volume = "124",
pages = "61--66",
journal = "Journal of Nutrition",
issn = "0022-3166",
publisher = "American Society for Nutrition",
number = "1",
}