Vitamin activities in human portal, hepatic and femoral blood after vitamin ingestion.
The dynamics of intestinal absorption, blood concentration and distribution of thiamin, biotin, nicotinate, riboflavin, pantothenate, various folates (folic acid, folinic acid, pteroyltriglutamate), vitamins A, E, C, B12, and B6 were monitored in 12 patients by multiple simultaneous sampling of blood obtained by combined catheterization of portal vein, hepatic vein, and femoral artery after vitamin ingestion. All water-soluble vitamins proved elevated after vitamin ingestion principally in portal blood within 10 minutes as compared with hepatic and femoral blood. Elevated vitamin levels in portal blood--compared to hepatic and femoral blood--remained high even after 120 min. indicating that absorption from the gut was still progressing. In contrast, ingestion of the fat-soluble vitamins A and E evoked no elevated vitamin activity in portal blood. Within 10 min. after vitamin ingestion, all folates were converted into reduced and methylated 5-methyltetrahydrofolate (5-CH3THF) on passage through the gut. At this time, portal blood elevation of 5-CH3THF persisted before its elevation in hepatic or femoral blood. Presumably, the elevation was not due to the flushing of stored 5-CH5THF from tissues but rather of folate conversion to 5-CH3THF upon gut passage. The significance of these findings is discussed.
Baker
H
H
Department of Preventive Medicine, University of Medicine and Dentistry, New Jersey Medical School, Newark.
tenHove
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W
Baker
E
E
Frank
O
O
D000284:Administration, Oral; D005268:Femoral Vein; D006503:Hepatic Veins; D006801:Humans; D007408:Intestinal Absorption; D011169:Portal Vein; D014815:Vitamins / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*
D014815:Vitamins