Studies in histochemistry. XXXVIII. Determination of succinic dehydrogenase in microgram amounts of tissue and its distribution in rat adrenal.

A considerable literature has developed on the use of tetrazolium compounds for localization of succinic dehydrogenase activity in tissues by staining reactions. However, there are relatively few reports on the use of these compounds for macroquantitative analysis of this enzyme (l-5). In the present report, a quantitative method applicable to microgram amounts of tissue, such as microtome sections, will be described. The application of this method to a study of the histological distribution of the enzyme in the adrenal gland of the rat will also be given. The quantitative tetrazolium methods are based on the reduction of tetrazolium compounds to water-insoluble colored formazans, when the former act as hydrogen acceptors during the enzymatic oxidation of succinate to fumarate. The formazan is extracted with a fat solvent and this solution is subjected to calorimetry. Advantages in the use of neotetrazolium over triphenyltetrazolium salts for quantitative work have been pointed out by Clock and Jensen (5) ; neotetrazolium was used in the present investigation. After difficulties encountered in the elaboration of the micromethod were resolved, a procedure was developed which proved to be relatively simple and rapid, as well as sensitive and accurate.