THE OXIDATION OF LACTATE AND α-GLYCEROPHOSPHATE BY RED AND WHITE SKELETAL MUSCLE: II. HISTOCHEMICAL STUDIES

Abstract

The use of phenazine methosulfate (PMS) in the histochemical demonstration of lactate and α-glycerophosphate dehydrogenases in skeletal muscle has been examined. When PMS is added to the conventional dehydrogenase reagents, these enzymes appear to be at least as active in the white fibers as in the red. In the absence of PMS, the red fibers appear to be much richer than the white in lactate and α-glycerophosphate dehydrogenase. The conventional methods without PMS apparently give a false impression of the distribution of diphosphopyridine nucleotide (DPN)-linked dehydrogenases in skeletal muscle because of their dependence on the indigenous tissue level and intracellular localization of reduced DPN (DPNH)-diaphorase. A leakage of both enzymes from the sections into the histochemical dehydrogenase reagents occurred both in the presence and absence of PMS. When allowances are made for such losses, it appears that the PMS results are compatible with other evidence that the glycolytic dehydrogenases are more active in white than in red skeletal muscle fibers and that these enzymes are largely confined to the cytoplasm.