Calcium release from the skeletons of rachitic puppies.
The experiment was carried out on 3-month old puppies. Control animals received a diet normal in calcium and vitamin D. The diet for one group of experimental animals was deficient in both calcium and vitamin D, while another experimental group was fed a diet deficient in calcium but with adequate vitamin D. The response of these animals to injected parathyroid extract was evaluated over a 4 month period. The serum calcium response fell after approximately 20 days in both the calcium-deficient (vitamin D-replete) and the calcium- and vitamin D-deficient animals. The effect on the parathyroid response of the addition of calcium or vitamin D in vitamin D- and calcium-deficient animals was also evaluated. The addition of vitamin D to rachitic animals did not restore the response to parathyroid extract; however, in calcium- and vitamin D-deficient animals with normal calcium levels there was a restored response to parathyroid extract. Morphologic studies were made of the bone at various times during the experimental period; the presence of osteoid tissue correlated with the absence of a response to injected parathyroid extract. The results suggest that parathyroid hormone acts independently and requires the presence of mineralized bone for its action in raising the serum calcium. Vitamin D appears to be important in the mineralization of new bone tissue.
D000818:Animals; D001842:Bone and Bones / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002136:Calcium, Dietary; D004032:Diet; D004285:Dogs; D010280:Parathyroid Glands / Q000502:physiology; D010281:Parathyroid Hormone / Q000627:therapeutic use; D012279:Rickets / Q000188:drug therapy / Q000378:metabolism*; D014807:Vitamin D / Q000627:therapeutic use
D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D014807:Vitamin D; D002118:Calcium