Influence of Dietary Calcium and Phosphorus upon Action of Vitamin D in Experimental Lead Poisoning

In the preceding paper 1 a marked effect of vitamin D on the blood and bone lead concentrations of lead-fed animals was demonstrated. In view of the great importance attached to the dietary calcium and phosphorus content in lead poisoning 2 , 3 , 4 investigations were undertaken to determine the part these factors play upon the previously noted action of the antirachitic vitamin.

The basal diet used in the previous experiment contained traces of calcium (0.03%) and small amounts of phosphorus (0.246%) to which basic lead carbonate was added. To this basal diet 2.5% of calcium carbonate was added to produce a high calcium low phosphorus diet; and 2.75% of anhydrous Na₂HPO₄ was added to produce the high phosphorus low calcium diet. The diets are described below:

Albino rats raised in our laboratory from an original Wistar strain were used. The mothers were kept on the stock diet of Bills, et a. 5 The young were weaned at 21 days, at which time they were placed on the stock diet. At the age of 23 to 25 days this was replaced by the experimental diets described above. One half of each group was given 33 Steenbock units of vitamin D. (Mead Johnson's 250 D-viosterol in halibut liver oil, diluted in maize oil.) After 23 to 2.5 days the animals were sacrificed. The lead content of the blood was determined by the method of Willoughby, et al. 6 The lead content of the femora was determined by a modification of the above method (to be described).

The results of the experiments are presented in Table I. The results of the experiments are presented in Table I.