Histophotometry--the method of choice in quantifying dehydrogenase histochemistry.

Succinate, malate, and lactate dehydrogenase were demonstrated histochemically and measured histophotometrically in the heart and skeletal muscle (m. extensor digitorum longus and m. soleus) of rats at different ages. To prove the value of histophotometry, the enzymes of the tissues were estimated biochemically. The gel film technique cannot sufficiently prevent the diffusion of the soluble enzymes (malate-, lactate dehydrogenase) out of the tissue sections. Because of the different mobility, various isoenzymes, histophotometry cannot give reliable results. But, as far as membrane-bound dehydrogenases (succinate dehydrogenase) are concerned, histophotometry is the method of choice for basic measurements as in routine practical work, especially with tissues where the enzyme activities are heterogeneously distributed, e.g. in different types of muscle fibres in skeletal muscles.