Abstract
This study aimed at elucidation of the fate of vitamin B_<12> taken up by the liver following intravenous administration together with intrinsic factor as originally described by Okuda. Rats were given ^<60>Co-labeled vitamin B_<12> mixed with a purified hog intrinsic factor preparation, in quantities sufficient to bind all the vitamin, and the radioactivity in the liver was followed for three weeks. It was found that the liver radioactivity gradually decreased with concomitant redistribution of radioactivity to other organs, and that the fecal excretion of radioactivity markedly increased by the intrinsic factor. Subsequent Studies demonstrated that choleresis increased the fecal excretion and that radioactivity appeared in bile promptly and in considerable quantities following intravenous administration of vitamin B_<12> and intrinsic factor. The possibility of an extraintestinal role of intrinsic factor and the site of vitamin B_<12> uptake inside the liver are discussed.
