Use of Tetrazolium Compounds in Oxidative Enzyme Histo- and Cyto- chemistry

Abstract

A NEW tetrazolium salt previously synthesized has been evaluated for its ability to overcome the technical and theoretical barriers of either the MTT-Co (ref. 1) or nitro-BT methods^2,3. This compound is TNBT or 2,2′,5-5′-tetra-p-nitrophenyl-3,3′ -(3,3′ -dimethoxy-4,4′-biphenylene)-ditetrazolium chloride (Fig. 1), the formazan of which is purplish black⁴. The TNBT used in the following investigations produced a brownish-black precipitate in tissue sections. Though quite low in water solubility, minimal concentrations of TNBT are required for the effective demonstration of the succinic dehydrogenase system in fresh, frozen sections of tissue of mammalian tissues or human vaginal smear preparations. The following were investigated in mouse myocardium and kidney: (1) effect of concentration of dye on the products of TNBT formazan in slices of these tissues; (2) effect of pH. on the reduction of TNBT by the succinic dehydrogenase system in tissue sections in the presence or absence of appropriate substrate; (3) solubility of TNBT formazan in aqueous, alcoholic and other organic solvents necessary for the effective resin-mounting of sections of tissue containing precipitates of formazan.