Irradiated ergosterol and calcium-free diet: effect on calcium and phosphorus metabolism.

BROWN AND SHOHL [1930] and Watchorn [1930] have shown that large doses of irradiated ergosterol lead to a decreased retention of calcium in rats, in spite of the calcification of certain tissues which takes place at the same time. It has been noted also by Brown and Shohl [1930], Duguid, Duggan and Gough [1930] and by Harris [1930] that the severity of the symptoms of hypervitaminosis D corresponds with the amount of calcium in the diet, and that in cases where the intake of calcium is very low, the symptoms are difficult or impossible to produce. Although in the absence of calcium from the diet, irradiated ergosterol in doses of 5 or 10 mg. appears to be non-toxic', it remained to be seen whether the metabolism of calcium and phosphorus was affected or not in these circumstances. Total balance experiments therefore have been carried out and are briefly described below. EXPERIMENTAL. Steenbock's rachitogenic diet [Steenbock and Black, 1925] was used as the basal diet, salts being added as required. It was found to be practically free from calcium, and to contain 60 mg. of phosphorus per 10 g. dry weight of food. This, though organic in form, can be utilised by the rat, and made it impossible to compare a high Ca: low P with a low Ca: high P diet as was at first hoped. Adult albino rats of 160-200 g. were used, divided into two groups A and B. To the basal diet of Group A was added calcium carbonate, so that 10 g. of food (dry weight) contained 49 mg. of calcium. For Group B inorganic phosphate was added bringing the total amount to 121-7 mg. P per 10 g. dry weight of food. No calcium was added. Group A served as a control to Group B. The general technique, including methods of analysis, was identical with that previously described [Watchorn, 1930]. The experimental period consisted of 4 weeks, one preliminary without excess vitamin, two weeks when 0 05 % irradiated ergosterol was added to the food, and one final "curative" or