Effect of Crystalline Vitamin B12 on Experimental Anemia in Mice.

Summary The number of red blood cells per unit volume, but not hemoglobin concentration, was increased by crystalline vit. B12 injected intraperitoneally into mice rendered anemic by the administration of phenylhydra-zine hydrochloride. The mice were maintained prior to and during the experiment on a chemically-defined diet probably containing a relatively small amount of vit. B12 but adequate quantities of other hematopoietic substances. The increase in red blood cells, particularly during the first 4 days of severe anemia, was found to be directly proportional to the amount of vit. B12 administered. These results suggested the possible development of an assay procedure for the determination of vit. B12.