Skeletal Calcium Turnover in Non-Growing Rats.

Abstract

Summary Total calcium and radioactive calcium contained in selected skeletal components and in the entire bodies was determined in non-growing female rats at intervals up to 210 days after administration of the radioistope. Evidence for fractions of skeletal calcium with markedly different rates of turnover was obtained from the changing rates with time in removal of radiocalcium from the skeleton and from comparisons of calcium specific activities of the skeleton and plasma of the animals sacrificed at increasing times after administration of the radiocalcium. In this study the effect of skeletal accretion was minimized. The results confirm those previously obtained when skeletal growth was a possible factor influencing the results. These findings and interpretations are consistent with the concept that the bone salt exchanges the calcium of crystal surfaces rapidly and that of the interior of crystals more slowly by recrys-tallization. The specific activities of different bones and the change in specific activity of the bones with time indicate that indicate that anatomical location of bone influences its calcium turnover.