Update on the Histoenzymatic Methods for Visualization of the Activity of Individual Mitochondrial Respiratory Chain Complexes in the Human Frozen Sections.

Investigation of mitochondrial metabolism perturbations and successful diagnosis of patients with mitochondrial abnormalities often requires assessment of human samples like muscle or liver biopsy as well as autopsy material. Immunohistochemical and histochemical examination is an important technique to investigate mitochondrial dysfunction that combined with spectrophotometric and Blue Native electrophoresis techniques can be an important tool to provide diagnosis of mitochondrial disorders. In this chapter, we focus on technical description of the methods that are suitable to detect the activity of complex I, II, and IV of mitochondrial respiratory chain in frozen sections of brain, heart, muscle, and liver biopsies/autopsy. The protocols provided can be useful not only for general assessment of mitochondrial activity in studied material, but they are also successfully used in the diagnostic procedures in case of suspicion of mitochondrial disorders. In the age of high-performance NGS sequencing, these methods can be used to confirm whether mutations are pathogenic by proving their impact on the activity of individual respiratory chain complexes.