Effect of different calcium intakes on bone mineral composition in rats with a calcitonin secreting tumour.
The effects of hypercalcitoninaemia and different calcium intakes on bone composition were studied in rats with and without a transplanted calcitonin secreting tumour (MCT). The serum concentrations of immunoreactive calcitonin (iCT) increased progressively after transplantation. After 32 weeks the serum iCT concentrations in MCT rats were about 5-fold higher and serum ionized calcium was significantly reduced compared to control animals. In rats with hypercalcitoninaemia eating a standard calcium (0.9%) diet for 32 weeks, the dry weight and calcium and sodium content of the long bones were reduced compared to control rats without tumours or rats with a prolactin secreting tumour. The feeding of low (0.09%), medium (0.4%) and high (1.8%) calcium diets to MCT-rats resulted in corresponding levels of total and ionized serum calcium, but there was no difference in iCT concentrations. The MCT-rats taking the low calcium diet had decreased bone mass and calcium content compared to the other dietary groups. In conclusion, rats on normal calcium intake and carrying a calcitonin secreting tumour, but not a prolactin secreting tumour, had reduced femoral dry weight and bone mineral calcium content. Different calcium intake regimens did not affect hypercalcitoninaemia due to a tumour, but parallel changes in femoral dry weight and calcium content were found.
D000818:Animals; D001842:Bone and Bones / Q000032:analysis*; D002116:Calcitonin / Q000378:metabolism*; D002118:Calcium / Q000032:analysis; D002136:Calcium, Dietary / Q000494:pharmacology*; D002850:Chromatography, Gel; D008297:Male; D008903:Minerals / Q000032:analysis*; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000032:analysis* / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats
D002136:Calcium, Dietary; D008903:Minerals; D002116:Calcitonin; D002118:Calcium