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A iB S T R A C T The effect of partial pancreatectomy(80-90%,) on vitamin Bn absorption was studied in the rat. The absorption of 5 ng of^'Co-labeled vitamin B1u 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 B,2 absorption in control rats. Chloramphenicol did not enhance vitamin B12 absorption in partially pancreatectomized rats with pancreatic extractimproved 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 corected 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. INTRODUCTIONAlthough several patients with pancreatic exocrine insufficiency have been noted to poorly absorb vitamin B,2 the importance of normal pancreatic function for optimal vitamin Bi absorption is generally not appreciated 1-5). Furthermore, the pathogenesis of the observed vitamin B12 absorptive defect has not been clarified.The relationship between the pancreas and the intestinal absorption of vitamin B12 was studied by measuring the absorption of this vitamin in rats subjected to partial pancreatectomy. The results demonstrate (a) that the partially pancreatectomized rat has a defect in vitamin B12 absorption, (b) that the administration of hog pancreatic extract restores vitamin B12 absorption to normal, (c) that intrinsic factor extracted from the gastric mucosa -of partially pancreatectomized rats stimulates vitamin Bn absorption in vitro, and (d) that gastric intrinsic factor stimulates vitamin B12 uptake in gut sacs prepared from partially pancreatectomized rats. These data indicate that partially pancreatectomized rats develop a defect in vitamin B12 absorption which is due to neither an alteration in gastric intrinsic factor activity nor to an impairment of the intrinsic factor-vitamin B12 receptor in the intestine.

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In contrast to rats, in which long-term oral administration of ximelagatran stimulates pancreatic growth and adenoma formation, in humans, ximelagatran does not increase plasma CCK concentrations and has no demonstrable trophic effect on the human pancreas.