Effect of dietary calcium deficiency on bone matrix-induced ectopic bone

The effect of dietary depletion of calcium on collagenous bone matrix-induced ectopic bone was studied, following thirty days of deficiency. While the molar ratio of phosphorus and calcium did not exhibit any significant differences between the control and experimental groups, individual concentrations of these minerals showed significant reduction in the ossicles derived from experimental rats. A concomitant decrease and increase in urinary excretion of calcium and phosphate was noted in the calcium deficient group; the serum levels of these parameters, however, were not affected. Both hexosamine and hydroxyproline levels appeared higher in calcium deficient ossicles. A significant elevation of alkaline and acid phosphatase as well as aryl sulfatase was observed in calcium deficient ossicles. There appeared to be no difference between control and experimental rats in the rate of calcification as measured by ⁴⁵Ca uptake. These results suggest that dietary deficiency induces significant resorption of ectopic bone without altering mineralization capacity. It is suggested that matrix-induced ectopic bone may be used as a suitable experimental model to study pathophysiology of bone loss under various experimental conditions.