HISTOCHEMICAL DEMONSTRATION OF ACID INORGANIC POLYPHOSPHATASE

Abstract

A substrate solution for histochemical staining of acid inorganic polyphosphatase is prepared by controlled precipitation at pH 3.9, from ingredients totaling .014 M. lead, .05 M. acetate, .02 M. phosphate in the form of Graham's salt, and sufficient nitric acid to titrate. The final concentration of polyphosphate in solution is estimated at 5 x 10–4 M. in terms of total phosphate. Inorganic polyphosphatase is stainable after a variety of fixation methods and paraffin embedding, but not after treatment with 70% and 80% ethyl alcohol or with excess substrate. The presence of a divalent metallic cofactor, which can be reversibly removed by water, is indicated.