In vitro Studies on the Role of Vitamin D in the Metabolism of Calcium and Phosphorus in the Eat Bones

Summary. The object of the work has been to investigate, by means of experiments in vitro, the effect of vitamin D on calcium and phosphorus metabolism in rat. The normal bone has the ability to take up calcium from the incubation solution under certain conditions and, on the other hand, to give up calcium into the calcium‐free incubation solution. The bone was not able to take up inorganic phosphorus in the incubation experiments. On the other hand the excretion of inorganic phosphorus into the solution could always be demonstrated—both in incubation solutions with and without phosphorus. The bones of rats which had received large amounts of vitamin D seemed to be able to take up relatively more calcium than the bones of normal rats. On the other hand it is possible that the bone is then to some extent more than normally able to take up calcium and phosphorus. With regard to the deficiency of vitamin D, a tendency towards a decreasing uptake of calcium and increased loss of calcium was noted. The experiments support the view that vitamin D has a direct influence upon the mineral metabolism of the bone.