title: Biochemical localization of aryl hydrocarbon hydroxylase in the intestinal epithelium of the rat.
abstract: The distribution of the carcinogen-metabolizing enzyme system, aryl hydrocarbon hydroxylase (AHH), was biochemically determined in the intestinal epithelium of the rat. A method of epithelial cell isolation in which fractions of cells are sequentially collected as a villus tip-to-crypt gradient was used. AHH activity was highest in the midvillus region, 40% lower at the villus tip, and practically nonexistent in the crypt region where active cell proliferation takes place. This distribution differed from those of sucrase and alkaline phosphatase (used here as markers for cellular differentiation), which were characteristically lowest in activity at the crypts and increased continuously to the villus tips. Conceivably, the midvillus peak of AHH activity may serve to protect or enhance the susceptibility of cells undergoing cell division in the nearby crypt regions, depending on whether the predominant function of AHH in the intestinal epithelium involves detoxication or activation of polyaromatic carcinogens.
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000032:analysis*; D001580:Benzopyrenes / Q000378:metabolism; D004848:Epithelium / Q000201:enzymology; D007413:Intestinal Mucosa / Q000201:enzymology; D007422:Intestines / Q000201:enzymology*; D051381:Rats
chemical_list: D001580:Benzopyrenes; D001189:Aryl Hydrocarbon Hydroxylases