Vitamin B₁₂-intrinsic factor studies with isolated perfused rat liver

¹ Department of Biochemistry, Jefferson Medical College, Philadelphia, Pennsylvania

Vitamin B₁₂-intrinsic factor relationships have been studied with the isolated perfused rat liver technique. Approximately 20 times more vitamin B₁₂ is absorbed by the liver in the presence of intrinsic factor than without it. Rapid and significant transfer of vitamin B₁₂ from liver to bile has been observed. The dose-response curve for this system is similar to that reported for the absorption of vitamin B₁₂ through the intestinal tract of pernicious anemia patients. The order and time of addition of vitamin B₁₂ and intrinsic factor to the perfusing blood is critical for absorption of vitamin B₁₂ by the liver. If vitamin B₁₂ is added first, binding substances in the blood rapidly make vitamin B₁₂ unavailable to intrinsic factor added subsequently. If intrinsic factor is added first, gradual inactivation or removal of intrinsic factor by the liver leads to a much slower decrease in efficiency of absorption of subsequently added vitamin B₁₂. These effects are similar to those reported on absorption of vitamin B₁₂ through the human intestinal tract.

Note:
With the Assistance of Louis J. Philipp