Liver Storage of Vitamin B 12 by the Rat. ∗

Abstract

Summary

The storage of vit. B₁₂ in rat liver was investigated after feeding rats graded levels of crystalline vit. B₁₂ or of crude supplements. The vit. B_12M potency was determined with L. leichmannii after short-term auto-claving of the liver homogenates at pH 7.0. The vit. B₁₂ potency was shown to increase as the level fed was increased. The values were only 1/10 to 1/20 those for beef liver, however, and the vit. B₁₂ potency of rat liver was not reduced appreciably by alkali treatment. Studies on the desoxyribonucleic acid levels in rat livers and studies with Euglena gracilis assays for vit. B₁₂ indicated that the vit. B₁₂ activity remaining, as determined with L. leichmannii after alkali treatment, may be due to the presence of alkali stable forms of vit. B₁₂ as well as to desoxyribosides. The liver weight was shown to be greater per unit of body weight for the rats fed the vit. B₁₂-deficient diet as compared to the optimum diet.