Abstract
Summary
Correlation of the effect of Vit. D in augmenting concentrations of citrate in plasma and bone with its antirachitic action has been studied. Rats were made rachitic by feeding a Vit. D deficient diet which was also low in available phosphorus. Addition of Cortisol to the diet of such rats reduced concentration of citrate in serum and also blocked the effect of Vit. D in increasing serum and bone citrate levels. Antirachitic action of Vit. D as measured by rise of serum phosphorus concentrations and by histological evidences of calcification of rachitic cartilage and osteoid was not suppressed by Cortisol. The antirachitic action of Vit. D and its effect upon citrate metabolism can, therefore, be separated. The tibias of Vit. D deficient Cortisol fed rats show evidences of increased calcification in comparison with rachitic controls which might in part be due to inhibition of bone resorption as well as retardation of cartilage growth by Cortisol. This increased calcification in Cortisol fed rats is associated with extreme depletion of extracellular phosphate.
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