Abstract
Sixteen specimens of normal rat bone were analyzed using the micro-technique described in previous communications.1,2 The age of the rats ranged from 1 day to maturity. A mean value of 1.99 ± 0.05 was obtained for the ratio residual Ca/P for these normal bones. In the adult rats, carbonate calcium constituted 15 to 16% of the total calcium; in the very young rats this value was only 8 to 10%. Transition values of 12 and 13% were obtained in rats 6 and 9 weeks old respectively. Since the proportion of calcium carbonate to calcium phosphate varies with age, it is incorrect to assign a definite constant formula to bone such as 3 Ca3(PO4)2 CaCO3. Bone apparently consists of at least two compounds whose proportions may vary independently. This is also borne out by the results reported by Howland, Marriott and Kramer. 3 They found that the bones of rachitic rats contain a smaller proportion of calcium phosphate to CaCO3 than do the bones of normal rats.
Twenty-five rachitic rats were fed cod-liver oil concentrate for 8 days. The rats were then autopsied and the “lines” of freshly deposited lime salts were removed and analyzed. The adjacent epiphyses and diaphyses were also removed and analyzed. Although the ratio for normal rats with this method had been established as described above, the shafts of the leg bones of the same animal were analyzed as an additional control. The values for residual Ca/P obtained were: 2.05 for the shafts; 2.10 for the epiphyses and diaphyses; and 2.38 for the test lines.
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