Effect of Toluidine Blue on Metastatic Calcification. ∗

Abstract

Summary and Conclusions

1. This experiment indicates that not only does toluidine blue fail to inhibit the metastatic calcification produced by parathormone, but that the deposition of calcium is augmented by the concurrent administration of the dye. Increased calcification was observed in the connective tissue ground substance of the kidney, stomach, spleen, arteries and heart. This was an unexpected result due to the observation of Miller(8) that treatment of hypertrophic rachitic cartilage slices with basic dyes inhibits subsequent calcification. The fact remains, however, that the acid mucopolysaccharide present in the connective tissue matrix has a strong affinity for basic dyes. Rubin and Howard(6) have shown that the increased intensity of toluidine blue staining in areas about to calcify suggest that new polysaccharide appears or that the chemical state of the polysaccharide already present changes. An alteration in chemical form of the matrix favors combination with calcium and confers the state of calcifiability on the matrix. Engel(4) has reported that parathormone depoly-merizes ground substance to increase calcifiability. It does not appear necessary therefore to infer competitive binding between toluidine blue and calcium for available reactive groups of the mucopolysaccharide. Concerning the data presented in this paper, toluidine blue apparently altered the chemical state of the ground substance, increased calcifiability, and exaggerated the parathormone effect. We have previously reported(12) that altering the connective tissue ground substance by compensatory renal hypertrophy or administration of desoxycorticosterone, increases or decreases, respectively, calcification produced by use of parathyroid extract. 2. The inhibitory effect of toluidine blue on the activity: of heparin has been described by Allen(13). Experiments now in progress indicate that augmentation of calcification in the basement membrane of large and small arteries by use of toluidine blue, as described in this paper, may be blocked by the concurrent administration of heparin.