Use of phenazine methosulfate in enzyme histochemistry of human muscle biopsies

Abstract

Tissue incubated in a medium for the histochemical demonstration of LDH [lactic dehydrogenase] to which PMS [phenazone methosulfate] was added cannot be used to give information with regard to the localization of the enzyme. Any incubating medium in which all the components of the enzyme system under investigation are soluble and which uses a substantive tetrazolium as an indicator, will probably result, in a direct NBT [nitro-blue tetrazolium] stain. The selective binding of tetrazolium salts to subcellular components may lead to certain difficulties in the interpretation of histochemical techniques employing these salts. Those components to which the tetrazolium salts do not bind cannot be demonstrated histochemically using the substantive tetrazolium compounds. PMS and cyanide, when incubated with a tissue section in the presence of NBT, will produce a well-marked direct NBT stain. The 2 compounds should not be used in conjunction in enzyme histochemistry. Variations in the concentration of the substances in the incubation media for demonstrating LDH production of almost any desired pattern of staining in straited muscle if PMS is present. A PMS shunt results in the oxidation of PMS preventing the reduction of NBT by PMS. This shunt is probably due to the action of part of the cytochrome chain.