Effect of Intrinsic Factor on Vit. B 12 Uptake by Rat Intestine in vitro. ∗

Abstract

Summary

Sacs of everted small intestine of the rat incubated in bicarbonate-saline containing glucose and B₁₂ showed only a very small B₁₂ uptake in the absence of a source of intrinsic factor. In the presence of neutralized rat gastric juice the stimulation of B₁₂ uptake was 10- to 25-fold. No B₁₂ appeared on the serosal side of the preparation. Stimulation of B₁₂ uptake was most marked in segments of intestine taken from the midportion of the small intestine. Evidence is presented that neither B₁₂ nor intrinsic factor when added alone are adsorbed to the intestinal wall but must be present simultaneously to give B₁₂ uptake.