1994 Volume 58 Issue 8 Pages 1357-1363
The dietary response of mucosal ornithine decarboxylase (ODC) in meal-fed and refed rats was investigated for each quarter of the small intestine. The intake of a normal powdered diet caused a considerable postprandial increase in the ODC activity in the mid two quarters, while the intragastric infusion of an aqueous solution containing amino acids and glucose elevated the ODC activity to a large extent in the proximal quarter as well as in its contiguous mid quarter. Such responsiveness was almost completely depressed by previous α-difluoromethylornithine (DFMO) administration. Mucosal scrapings from the small intestine of rats with ODC depression did not significantly differ from those without ODC depression as to their [3H]thymidine-, [3H]uridine-, and [3H]leucine-incorporating capacity into the DNA, RNA, and protein fractions, respectively, at various postprandial times. On the other hand, putrescine was found to plentifully accumulate in the ileal lumen within a few hours after the start of eating, suggesting that the ODC depression would thereby have been compensated. To investigate this further, putrescine-uptake experiments were carried out with both everted sacs and in situ loops of the small intestine. It is assumed from the results that [14C]putrescine was transported a little more across the ileal wall than across the duodenal or jejunal wall by a Na+- or energy-independent mechanism, and that [14C]putrescine taken up from the lumen distributed itself within the whole body.
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