Abstract
Summary
Ligated intestinal segments in rats were prepared without disturbing the vascular or lymphatic supply. The pH of the contents of the lumen, measured immediately after excision of the segment, ranged from 5.96 in the proximal jejunum to 7.24 in the terminal ileum. Introduction of an acid phosphate buffer reduced the pH of all segments to the range 5.95-6.19. Tris (hydroxymethyl) aminomethane increased the pH to the range 7.03-7.6. Acid phosphate decreased the absorption rate of Sr whereas the alkaline Tris reagent increased absorption of both Sr and Ca from all segments except from the duodenum, which appears to have a maximum limiting rate. Intubation experiments confirmed the results obtained with ligated segments: the total absorptive capacity of the small intestine for these ions is decreased by acid phosphate and increased by the alkaline Tris reagent.
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