Studies on the effect of vitamin D on calcium absorption and transport |
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Authors: | George Hashim and Irwin Clark |
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Institution: | Institute of Nutrition Sciences and Departments of Biochemistry and Orthopaedic Surgery, Columbia University, New York, N.Y. 10032, U.S.A. |
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Abstract: | 1. Mucosal cells of the small intestine obtained from rats deprived of vitamin D or given excessive amounts of the vitamin accumulated significantly more calcium than did cells from control animals. 2. Mucosal cells from vitamin D-deficient rats released less calcium than did cells from normal or hypervitaminotic D animals. 3. Studies in vivo showed that the transfer of (45)Ca from the intestine to the blood was delayed in vitamin D deficiency, but was accelerated in hypervitaminosis D. 4. The findings support the thesis that vitamin D is involved in the release of calcium rather than in its uptake by mucosal cells. 5. Further evidence is presented suggesting that uptake of calcium by intestinal mucosal cells at 0 degrees is primarily passive, whereas at 38 degrees uptake and release are effected by an active process that depends on energy derived from glycolytic activity. |
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