Light and electron microscopical demonstration of the ouabain-sensitive, potassium-dependent p-nitrophenylphosphatase activity (K-NPPase) using a Ce-Mg-double capture technique.

The cerium-based method of Kobayashi et al. for the histochemical demonstration of K-NPPase activity was improved. Besides Ce3+ additionally Mg2+ ions as orthophosphate capture were employed (double capture technique). For light microscopical purposes the Mg-phosphate was converted into Ce-phosphate by treatment of the sections with Ce-citrate yielding higher quantity of reaction product. Unspecific background staining was eliminated by EGTA. In the electron microscope this technique brought about fine granular reaction products without diffusion artefacts.