Steady-state relationship of calcium-45 between bone and blood: differences in growing dogs, chicks, and rats

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Science  09 Oct 1981:
Vol. 214, Issue 4517, pp. 190-193
DOI: 10.1126/science.6792709


In young animals that had received multiple doses of calcium-45, a constant ratio of calcium-45 specific activity in blood to that in bone was found in growing dogs and chicks but not in rats. This steady-state relationship of calcium-45 between bone and blood suggests that during growth in dogs and chicks most of the skeletal calcium is in an active state of turnover. In growing rats, after the first 2 weeks of life, the blood/bone ratio of calcium-45 decreases due to a decrease in bone resorption.