Further Observations on Distribution of Radioactivity Following Parenteral Administration of Co 60 Vitamin B 12 . ∗

Abstract

Conclusions

(1) Prior administration of 30 μg of “cold” B₁₂ or 10 mg of amethopterin daily for 1 week, or injection of 1 mg of “cold” B₁₂ 7 days after intramuscular injection of 1 μg of Co⁶⁰ vit. B₁₂, does not alter rate of disappearance from site of injection or pattern of distribution of radioactivity over liver, spleen and left kidney. (2) Intravenous injection of 1 μg of Co⁶⁰ B₁₂ is followed by a more rapid appearance of radioactivity over the organs named. (3) Intramuscular injection of 1 mg of “cold” B₁₂ simultaneous with 1, 2 or 24 hours after the administration of 1 μg of Co⁶⁰ B₁₂ reduces height of radioactivity over organs named but does not prevent its localization there.