title: Some nutritional effects of folate-binding protein in bovine milk on the bioavailability of folate to rats.
abstract: The excretions of folate compounds into both the urine and bile were investigated in rats after the administration of pteroylglutamic acid (PteGlu) with or without the folate-binding protein (FBP) prepared from bovine milk. When the sample solution, containing either free or bound [3H]PteGlu (i.e., bound to the FBP from milk), was delivered to rats intragastrically via oral intubation, the amounts of [3H]PteGlu excreted into the feces did not change. On the other hand, the urinary excretion of 3H-labeled folate compounds, especially [3H]5-methyltetrahydrofolic acid (5-CH3-H4PteGlu), after the administration of bound [3H]PteGlu was significantly lower (P less than 0.01) than that after the administration of free [3H]PteGlu. The urinary excretion of [3H]5-CH3-H4PteGlu was directly proportional to the initial amount of free [3H]PteGlu administered. The similar effect of FBP was also observed when the biliary excretion of 3H-labeled folate compounds was investigated in situ. Furthermore, the incorporation of [3H]PteGlu into folate-requiring intestinal microorganisms was considerably reduced when it was bound to FBP. These results suggest that milk FBP has some nutritional effects on the bioavailability of folate in vivo.
mesh_terms: D000818:Animals; D001682:Biological Availability; D002250:Carbon Radioisotopes; D002352:Carrier Proteins / Q000494:pharmacology*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D058973:Folate Receptors, GPI-Anchored; D005492:Folic Acid / Q000378:metabolism*; D007778:Lactobacillus / Q000187:drug effects; D008297:Male; D008892:Milk; D011624:Pteroylpolyglutamic Acids / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface; D014316:Tritium
chemical_list: D002250:Carbon Radioisotopes; D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D011624:Pteroylpolyglutamic Acids; D011956:Receptors, Cell Surface; D014316:Tritium; D005492:Folic Acid