MECHANISM OF THE HETEROTOPIC CALCIFICATION INDUCED BY SUBCUTANEOUS INJECTION OF LEAD ACETATE

Abstract

Heterotopically calcified tissues produced by subcutaneous injection of lead acetate in the rats were studied. The total dry weight and total minerals in the calcified tissues showed a significant increase until 32 days after injection of lead acetate. On the other hand, changes in the Ca/ P, Ca/ash, and P/ash ratios in the calcified tissues can be classified into two stages, and the amount of injected lead decreased until 32 days after the injection. The leakage of Evans Blue was observed at the site of lead acetate injection for 2 days and the fluorescence of rhodamine was not seen in the calcified tissues. These phenomena suggested that mast cells and mediators of delayed hypersensitivity reactions played some role in the supply of calcium and phosphate from circulating blood and that acidic mucopolysaccharides as a main constituent of matrix of calcified tissue seemed not to be produced during the development of the heterotopic calcification induced by lead acetate. Finally, the possible mechanisms of the heterotopic calcification are discussed.