A METHOD FOR THE HISTOCHEMICAL DEMONSTRATION OF TRIPHOSPHOPYRIDINE NUCLEOTIDE-LINKED l -HEXONATE DEHYDROGENASE ACTIVITY IN KIDNEYS OF SEVERAL SPECIES

The described technique utilizes a tetrazolium salt to localize TPN²-linked l-hexonate dehydrogenase activity in unfixed frozen sections of mammalian kidneys. Enzyme diffusion was kept at a minimum by adding PVP to the incubation medium in a final concentration of 20%. Nevertheless, the sites of enzyme activity could not be localized precisely at the cell level. Histochemical evidence for l-hexonate specificity of the enzyme has been presented.

A survey of various mammalian tissues revealed strong enzyme activity in the renal cortex of hamsters, rabbits, dogs and humans. In guinea pigs, the histochemical reaction was considerably weaker in heterozygous albino males than in pigmented ones. No enzyme activity was demonstrable in any of the female guinea pigs. Otherwise, the intensity of the histochemical reaction was consistent for a particular species. Although striking species differences were seen in the enzyme distribution pattern, activity was always limited to the epithelial cells of the renal cortex. Other tissues, known to contain the enzyme, failed to reveal an unequivocal histochemical reaction.