Development of a technique for in situ studies of calcium absorption in the intestine of rats.

The aim of the present study was to develop (feasibility, reliability, reproducibility) a technique for the in situ measurement of intestinal calcium absorption in the rat. An intestinal loop (duodenum+proximal jejunum) was perfused both by the intraluminal and vascular routes. A solution of NaCl 155 mM and CaCl2 1.25 mM containing 45Ca was perfused intraluminally at a flow rate of 0.2 ml/min and the 45Ca appearing in the venous effluent was determined to estimate calcium absorption. This technique was used to study the effect of a 10-day period of calcium supplementation on calcium absorption. The animals received enterally either 5 or 30 mg/day per kg BW. The results showed that intestinal calcium transport was enhanced when rats were given the calcium supplement for 10 days prior to the experiment (99.3 +/- 2.5 (n = 5) versus 36.6 +/- 3.6 (n = 5) nmol/min per kg BW, P < 0.001). This study indicates that dietary calcium supplement enhances calcium absorption probably by increasing the passive transport of calcium in the small intestine.journal article1993importe