Effect of Chelating Agents on Uptake of Ca 45 and Sr 85 by Defatted Bone in vitro. ∗

Abstract

Summary

The presence of chelating agents in buffered solutions affected the relative uptake of Ca⁴⁵ and Sr⁸⁵ by defatted bone powder. Strong chelating agents, like ethylenediaminetetraacetic acid and cyclohexanediaminetetraacetic acid, decreased the ratio of Ca⁴⁵/Sr⁸⁵ uptake considerably in presence of Ca, Ca plus Sr, or Sr carrier. Citrate and adenosinetriphosphate had similar but weaker effects. No effect was shown by glucose, lactate, gluconate, bicarbonate, bicarbonate plus phosphate, glutamate, aspartate, borate, glycerophosphate, lysine or glutathione. Those compounds which showed no effect had stability constants for Ca of less than 3. Strong chelating agents also decreased the relative amount of Sr⁸⁵ removed from defatted bone powder by exchange. Results indicate that natural chelating agents may be partly responsible for the low Ca⁴⁵/Sr⁸⁵ uptake ratio by bone from serum compared with uptake from synthetic inorganic solutions and emphasize the difficulty of removing Sr⁸⁵ from bone with chelating agents now available.