[Inhibition of calcium absorption and conditions of its prolongation in the presence of carbohydrate].

Experiments were performed on adult rats. In situ ligatured ileal loops were injected with a solution 10 mM CaCl2 containing 45Ca either with or without L-xylose in concentrations of 25, 50 or 100 mM L-xylose. The rats were sacrified at either 0.5, 1.0, 1.5 or 2.0 hours after injection; the entire loop including the wall and content was removed. After ashing, the radioactivity of the loop was measured and the absorption coefficient of 45Ca was calculated. After half an hour, the absorption coefficient of the four solutions had about the same value. At this time, the 45Ca absorption was completed with the solution containing only calcium. With the solution containing pentose, the 45Ca absorption continued for a longer period of time. The maximal values of absorption coefficient were obtained after one hour with 25 and 50 mM L-xylose and after one and a half hour with 100 mM L-xylose; similarly, the maximal values increased in proportion to the concentration of pentose in the solution. The contents of the loops were fractionated successively by centrifugation, ultracentrifugation and two membrane ultrafiltration. No differences were observed between the repartition of 40Ca or 45Ca, either with or without 50 mM L-xylose. The stop or the lengthening of the absorption could be attributed to a possible influence of carbohydrate upon the mechanism of calcium transfer. This question is discussed from the point of relationship between the carbohydrate and the intestinal alkaline phosphatase.