The Role of the Pancreas in Vitamin B<sub>12</sub> Absorption: Studies of Vitamin B<sub>12</sub> Absorption in Partially Pancreatectomized Rats

Philip P. Toskes; Julius J. Deren

doi:10.1172/JCI106806

The Role of the Pancreas in Vitamin B₁₂ Absorption: Studies of Vitamin B₁₂ Absorption in Partially Pancreatectomized Rats

Philip P. Toskes and Julius J. Deren

Published February 1, 1972 - More info

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Abstract

The effect of partial pancreatectomy (80-90%) on vitamin B₁₂ absorption was studied in the rat. The absorption of 5 ng of ⁵⁷Co-labeled vitamin B₁₂ was significantly reduced from 70 ±2.5% (mean ±SE) in control and sham-operated rats to 32 ±2.6% in partially pancreatectomized rats. Hog pancreatic extract (0.17 g/kg) improved vitamin B₁₂ absorption from 30.0 to 61.0% in partially pancreatectomized rats but did not alter vitamin B₁₂ absorption in control rats. Chloramphenicol did not enhance vitamin B₁₂ absorption in partially pancreatectomized rats with pancreatic extract-improved vitamin B₁₂ malabsorption. The partially pancreatectomized rats with pancreatic extract-improved vitamin B₁₂ malabsorption were sacrificed and the stomach and small bowel studied in vitro to further define the pathogenesis of the vitamin B₁₂ malabsorption. Rat gastric intrinsic factor stimulated vitamin B₁₂ uptake by intestinal sacs prepared from partially pancreatectomized rats 3.1-fold. Gastric intrinsic factor prepared from partially pancreatectomized rats was as effective in promoting vitamin B₁₂ uptake by rat intestinal sacs as intrinsic factor prepared from control rats. These data indicate that partially pancreatectomized rats develop an abnormality in the absorption of labeled vitamin B₁₂ which can be corrected by pancreatic extract. The vitamin B₁₂ malabsorption is due to neither an alteration in gastric intrinsic factor activity nor an impairment of the intrinsic factor-vitamin B₁₂ receptor in the intestine. It is suggested that in the partially pancreatectomized rats the intrinsic factor-vitamin B₁₂ complex exists in a form which is not available for absorption.