Abstract
Single or multiple intraperitoneal injections of lactose failed to stimulate the absorption of calcium from the intestine of the rat. Daily intraperitoneal doses of lactose, given for a period of two weeks, failed to influence the mobilization of labeled calcium from the skeleton of the male rats. Calcium absorption from the ileum could be stimulated only if calcium and lactose were together in the same segment; if in adjacent segments no effect was observed. Rats fed for two weeks on a diet containing 10% of lactose did not absorb a greater proportion of a test dose of Ca*Cl2 than did rats fed a diet containing 10% of glucose. The enhancing effect of lactose was not limited to calcium but included magnesium, strontium, barium and radium. Lysine resembled lactose but failed to stimulate the absorption of magnesium. It was concluded that the site of action of lactose is in the intestine and not within the body.