Stability of Injected Vitamin B 12 -Co 60 and Vitamin B 12 Content of Dog Liver

Abstract

Summary

Vit. B₁₂-Co⁶⁰ injected intravenously into dogs is retained by dog livers as an intact cobalamin, probably as cyanocobalamin. This was demonstrated by the method of reverse isotope dilution. Direct isotope dilution indicates an average total cobalamin concentration of 0.36 μg/g of dog liver. The authenticity of retained Vit. B₁₂-Co⁶⁰, introduced by injection, as an isotope dilution tracer was demonstrated by simultaneous analysis with Vit. B₁₂-CO⁵⁷. Degradation of Vit. B₁₂ to ionic, cobalt is negligible.

The authors are greatly indebted to Mrs. Helen R Skeggs, Merck Sharp & Dohme Research Laboratories, for microbiolcgical assays. They wish to acknowledge the assistance of Mr. P. G. Gethard from these same laboratories for certain isolations and measurements contributing to Table II.