HISTOCHEMICAL LOCALIZATION OF SPECIFIC OXIDATIVE ENZYMES. V. THE DISSOCIATION OF SUCCINIC DEHYDROGENASE FROM CARRIERS BY LIPASE AND THE SPECIFIC HISTOCHEMICAL LOCALIZATION OF THE DEHYDROGENASE WITH PHENAZINE METHOSULFATE AND TETRAZOLIUM SALTS

Incubation of frozen sections of rat kidney with lipase abolishes the staining reaction for the succinic dehydrogenase system with blue tetrazolium alone or blue tetrazolium plus methylene blue, pyocyanin, Janus green B, azure C or azure B bromide. In contrast, staining with phenazine methosulfate plus blue tetrazolium is unaffected by prior incubation with lipase. Qualitatively similar results were obtained with neotetrazolium.

Particulate preparations of rat liver and kidney, normally capable of reducing either methylene blue or phenazine methosulfate in the presence of succinate, lose the ability to reduce methylene blue after incubation with lipase. In contrast, the reduction of phenazine methosulfate is unaffected by this treatment.

The succinic dehydrogenase activity of frozen sections of Ascaris lumbricoides or of homogenates of Ascaris muscle, unlike rat kidney and liver, is unaffected by incubation with lipase and differs in this respect from purified preparations of Ascaris succinoxidase which are dissociated into succinic dehydrogenase and one or more carriers by treatment with lipase.

The results support the conclusion that the succinic dehydrogenase system contains carriers linked to the dehydrogenase. The carrier is essential for reduction of blue or neo-tetrazolium alone or in combination with several soluble oxidation-reduction dyes and is localized in tissue sections by these agents. The dehydrogenase can reduce phenazine methosulfate and this dye coupled to a tetrazolium salt can be used for the histochemical localization of succinic dehydrogenase in tissues.