title: Presence of cytochrome P-450-dependent monooxygenase in intimal cells of the hog aorta.
abstract: Cytochrome P-450-dependent mixed function oxidase activity is present in vascular tissue; however, as far as we could determine, the distribution of monooxygenase activity across the blood vessel wall has not previously been assessed. The aryl-hydrocarbon hydroxylase activity was examined by metabolism of benzo[a]pyrene in microsomes prepared from intimal and smooth muscle cell scrapings of the hog thoracic aorta. Microsomes of intimal cells comprising 95% endothelial cells showed an approximately 2.5-fold increase in aryl-hydrocarbon hydroxylase activity compared with that in microsomes prepared from medial smooth muscle cells. Michaelis-Mentin kinetics for the intimal enzyme yielded an apparent Km value of 11.11 microM and an apparent Vmax of 3-OH benzo[a]pyrene of 40 pmol/mg protein/10 min. Aryl-hydrocarbon hydroxylase activity was dependent on nicotinamide adenine dinucleotide phosphate and was inhibited by 7,8 benzoflavone, SKF 525A, and carbon monoxide. The localization of cytochrome P-450-dependent mixed function oxidase primarily to the intimal surface of the aorta may indicate a role for this enzyme system in vasoregulation and the pathogenesis of atherosclerosis.
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000201:enzymology*; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D001564:Benzo(a)pyrene; D004727:Endothelium / Q000201:enzymology; D066298:In Vitro Techniques; D008297:Male; D008861:Microsomes / Q000201:enzymology; D009130:Muscle, Smooth / Q000201:enzymology; D013552:Swine
chemical_list: D001564:Benzo(a)pyrene; D001189:Aryl Hydrocarbon Hydroxylases