Phenazine Methosulfate; its Use in Evaluating Activity of Dehydrogenase Systems of Avian Liver

Lactate dehydrogenase (LDH), malate dehydrogenase (MDH) and suecinate dehydrogenase were demonstrated in livers of 15-day chick embryos. The addition of phenazine methosulfate (PMS) to the LDH and MDH incubation mixtures reduced diformazan deposition in the liver epithelium but not in connective tissue. A 30 sec formalin fixation, absence of PMS, or the addition of sodium azide or potassium cyanide to the PMS-containing incubation mixtures facilitated formazan deposition. These results are explained by assuming that, in the absence of PMS, dehydrogenase activity is demonstrated via endogenous diaphorase. When PMS is present, Nitro BT reduction occurs within the incubation mixture. A side effect of the azide or cyanide is an interference with, the action of PMS, thus allowing diformazan deposition via the endogenous diaphorase when this is present in the tissue.