Selective Uptake of Specifically Bound Cobalt-58 Vitamin B₁₂ by Human and Mouse Tumour Cells

Abstract

MANY body fluids have been reported to contain substances that combine with vitamin B₁₂. However, research concerning the role of these substances in the absorption of vitamin B₁₂ by animal cells has been confined mainly to work involving intrinsic factor preparations or normal human gastric juice. A large amount of evidence has led to general acceptance that vitamin B₁₂ bound to intrinsic factor is taken up by intestinal mucosa cells to a greater extent than unbound vitamin B₁₂ (ref. 1). Intrinsic factor also has been shown to promote uptake of vitamin B₁₂ by rat liver slices^2,3 and liver homogenates⁴. The latter process apparently is not influenced by changes of temperature, and it is not affected by metabolic inhibitors such as 2,4-dinitrophenol³.