Localization of Diamine Oxidase and D-Amino Acid Oxidase in Kidney, Demonstrated by Means of Immunohistochemical Method

The localization of both diamine oxidase and D-amino acid oxidase was examined by immunofluorescent technique on the frozen section of the porcine kidney.The cells, composing the Bowman's capsule and the proximal convoluted tubule, showed intense fluorescence which showed the localization of diamine oxidase. The antigen was concentrated in the supra- and para-nuclear cytoplasm. But, unlike monoamine oxidase, diamine oxidase may not be located in the mitochondria, because higher concentration of diamine oxidase is found in the apical cytoplasm where the mitochondria are not so much observed.The D-amino acid oxidase was demonstrated in the apical cytoplasm of the cells constituting the Bowman's capsule, the proximal convoluted tubule and a part of the Henle's loop.The place where two enzymes were located was, as mentioned above, mostly in the proximal convoluted tubule. At this place, the large amount of ammonia was reported to be secreted and the highest activity of the two enzymes was also encountered. In other words, the location of two enzyme proteins, the place where ammonia is eliminated and the sites of enzymatic activity of two enzymes were quite identical.