SITES OF CALCIUM ABSORPTION AND THE CALCIUM CONCENTRATION OF GUT CONTENTS IN THE DOG

Abstract

Physiological concentrations of calcium were measured in the lumen of the intestine of dogs which had been fed low, normal, or high levels of calcium. The rates of Ca absorption from duodenal, jejunal, or ileal Thiry-Vella fistulae were also determined. These data demonstrate that high Ca concentrations usually exist in the intestinal tract, and that the concentration in the lumen is directly affected by dietary level of Ca. The rate of calcium absorption per cm length of duodenum was almost double that in the jejunum or ileum, but the estimated effective Ca absorption in the whole ileum (744 mg/6 hours) exceeded that in the jejunum (144 mg/6 hours) and that in the duodenum (36 mg/6 hours).