Stimulation of Vit. B 12 Uptake in Tissue Slices by Intrinsic Factor Concentrate. ∗

Abstract

Summary

It was demonstrated that intrinsic factor concentrate stimulates the uptake of radioactive vit. B₁₂ in slices of rat liver and kidney, in vitro. Evidence presented indicates the specificity of this stimulatory action. The stimulation is a function of concentration of intrinsic factor concentrate added, and may therefore be the basis of an in vitro assay for intrinsic factor. It was not necessary to use vit. B₁₂ deficient tissues to show the stimulation effect and it was observed that hyperthyroidism caused increased uptake of vit. B₁₂ in the absence of added intrinsic factor concentrate. A brief discussion of the possible function of intrinsic factor was presented.