THE DISTRIBUTION OF ADMINISTERED VITAMIN K1-C14 IN RATS

Abstract

Radioactive vitamin K1-C14 was administered orally, intramuscularly, and intravenously to albino rats and the distribution of radioactive C14 determined. Isotope dilution studies were performed to ascertain the degree to which the vitamin K1-C14 was present in unchanged form in some tissues. Regardless of the route of administration, radioactivity was deposited in all the tissues. The liver accumulated the largest amounts of radioactivity but the spleen had a much higher specific activity following intravenous administration of the vitamin. Radioactivity could be detected in the liver for as long as 12 days after administration. When the log of the dose of vitamin K1-C14 (5.6–82 mgm./kgm.) was plotted against the log of the vitamin K1 equivalent in the various tissues a straight line relationship was obtained. The per cent of the injected dose present in the tissues 24 hr. after injection was as follows: liver 2.8, skeletal muscle 12.2, small intestine and contents 2.5, bile 26, feces 6.2, urine 0.98. The per cent of such activity present as unchanged vitamin K1-C14, as judged by isotope dilution tests, was liver 78, skeletal muscle 74, small intestine and contents 15, bile 1.5, feces 6.5, and urine 0.0.