[Improved demonstration of topochemical dehydrogenase in the CNS with a nitro-monotetrazolium salt]

Succinate dehydrogenase (SDH) and glutamate dehydrogenase (GDH) were determined parallel to the tetrazolium salts p-DNTT, NBT and TNBT under different conditions using sagittal brain sections of newborn and 3 till 100-day-old rats. Under conventional incubation conditions for SDH (37 degrees C, 30 min), the tetrazolium salts p-DNTT stained more intensely than NBT or TNBT. Decrease of the final concentration of tetrazolium salts from 1.2 mmol/l to 0.6 mM effected a considerable increase of p-DNTT formazan development. Using NBT or TNBT, the formazan formation was significantly smaller. In contrast to SDH the demonstration of GDH activity under incubations conditions mentioned is unsatisfactory at any rate. Preservation of mitochondria during the preparation and incubation procedure improved evidently the quality of the GDH-demonstration, especially by use of p-DNTT. The formazan of p-DNTT was formed to be amorphous and was confined exclusively to enzyme containing compartments, whereas formazanes of the NBT and TNBT spread out more diffusely.