Calcification. XII. Cation-Linked Inhibition by Fluoride and Cyanide Ions in β-Glycerophosphate Medium. ∗

Summary

1. The influence of several ions on in vitro calcification in β-glycerophosphate medium has been compared to their effects in inorganic phosphate solution at two phosphate levels which yield comparable degrees of calcification, viz., 10/5/0-10/0/5.5 and 10/8/0-10/0/10. Cyanide ion did not interfere in the absence of magnesium. When magnesium was present there was a partial block of calcification at the lower organic phosphate level equivalent to that obtained in the corresponding inorganic solution. At the higher phosphorus levels, 10/8/0-10/0/10, virtually no inhibition by the magnesium-cyanide couple was evident. 2. Calcification in the dilute glycerophosphate solution (10/0/5.5) was blocked by fluoride in the presence of magnesium. In the absence of magnesium, inhibition by 10⁻⁴ molar fluoride was noted during the first few hours, but not evident on prolonged incubation. Mineral deposition with l0⁻³ molar fluoride in the absence of magnesium exceeded that obtained with the fluoride-free control. Essentially similar results were presented earlier for the equivalent inorganic mineral solution, 10/5/0(1). At higher inorganic and organic phosphorus levels the fluoride block in the presence of magnesium was partially overcome. 3. The data indicate a striking similarity in the response of the calcifying mechanism in both inorganic and β-glycerophosphate media to the action of fluoride or cyanide ions in the presence and absence of magnesium. It therefore appears questionable whether one may, at this time, associate the calcification process in inorganic phosphate and glycerophosphate solutions with two completely discrete mechanisms. 4. Strontium, barium, and manganous ions share with magnesium the property of mediating the cyanide inhibition of calcification.