Effect of condensed phosphates on calcification of chick embryo femurs in tissue culture

Abstract

Previous work had shown that condensed phosphates (pyrophosphate and polyphosphates) inhibit calcium phosphate precipitation in vitro. Graham salt, a long-chain polyphosphate, and inorganic pyrophosphate have now been tested for their effect on the growth and calcification of embryonic chick femurs grown in tissue culture. At 4 and 16 u[mu]g P/ml they caused strong inhibition of calcification, whether this was assessed morphologically or by means of X-ray diffraction. In contrast at I [mu]g P/ml, both condensed phosphates caused a small activation of mineral deposition. At all concentrations tested these compounds had no significant effect on growth and hydroxyproline content. These results support our former hypothesis that pyrophosphate is one of the physiological regulators of calcification.