Vitamin B12 Biosynthesis after Oral and Intravenous Administration of Inorganic Co60 to Sheep.

Publisher Website
Google Scholar
Abstract
1. Excretions and tissues from wether lambs dosed orally and intravenously with inorganic cobalt-60 were measured for total radioactivity and also for radioactivity in fractions characterized chemically as vit. B12-like, inorganic and bound. 2. After oral administration there was considerable biosynthesis of vit. B12 in the tract, probably occurring mainly in the rumen. After intravenous administration there was only slight, if any, biosynthesis in the tract, but considerable formation of vit. B12 in the tissues with the suggestion that the adrenals and spleen were mainly responsible. Overall, there was more than 10 times as much Co60 converted to B12 after ingestion than after intravenous administration. 3. The concentrations of vit. B12-like Co60 in the tissues after intravenous injection were slightly higher than after ingestion of equal amounts of Co60. 4. In the light of results on the response of cobalt-deficient lambs to parenterally administered vit. B12, it is suggested that the vit. B12-like material synthesized by the tissues from inorganic cobalt is physiologically ineffective in relieving cobalt-deficiency symptoms in sheep.