COMPARATIVE LOCALIZATION OF ALDEHYDE OXIDASE AND XANTHINE OXIDOREDUCTASE ACTIVITY IN RAT-TISSUES

The distribution of aldehyde oxidase activity was evaluated in unfixed cryostat sections from tissues of male Wistar rats using a tissue pro tectant, polyvinyl alcohol, with Tetranitro BT as a final electron acc eptor. The distribution of aldehyde oxidase activity was compared with that of xanthine oxidoreductase. The enzyme histochemical method demo nstrated aldehyde oxidase activity in the epithelium of the tongue, re nal tubules and bronchioles, as well as in the cytoplasm of liver cell s. Such activity was not detected in oesophagus, stomach, spleen, adre nal glands, small or large intestine or skeletal and heart muscle fibr es. In contrast, xanthine oxidoreductase activity was demonstrated in the tongue, renal tubules, bronchioles, oesophageal, gastric, small an d large intestinal epithelial cells, adrenal glands, spleen and liver cytoplasm but not in skeletal and heart muscle fibres. The significanc e of the ubiquitous distribution of aldehyde oxidase activity, especia lly in surface epithelial cells from various tissues, except for the g astrointestinal tract, is unclear. However, aldehyde oxidase may posse ss some physiological activity other than in the metabolism of N-heter ocyclics or of certain drugs. (C) 1998 Chapman & Hall.