Benzo(a)pyrene Metabolism in Bovine Aortic Endothelial and Bovine Lung Fibroblast-like Cell Cultures1

such as the 7,8-diol, may be further metabolized to reactive intermediates that bind covalently to cellular nucleic acids and proteins (11, 19, 37, 41 , 42). The relative proportions of the various hydrocarbon metabolism pathways may determine whether the hydrocarbon will be detoxified or will induce dam age (20, 22, 28). Thus, it is essential to understand how cells from different tissues metabolize polycyclic aromatic hydrocar bons. The endothelium, which forms the luminal surfaces of the vascular and lymphatic systems, is particularly germane to studies of chemical carcinogenesis. It is the target tissue in humans for carcinogens such as vinyl chloride (17), and its unique and strategic location dictates that carcinogens passing to and from the blood stream will traverse endothelial cells. Juchau et al. (29, 30) have shown that polycyclic hydrocarbons are metabolized by aortic tissue of several species, and they have postulated that polycyclic hydrocarbons may have a role in the genesis of atherosclerotic lesions (29). If endothelial cells activate compounds to proximate or ultimate carcinogens, they could serve both as target cells and as a source of activated metabolites that pass into the blood stream to other tissues. Recent improvements in the cultivation of endothelial cells provide an opportunity to study endothelial cell functions in vitro (21). In this study, the metabolism of BP by a cloned strain of bovine fetal vascular endothelial cells (31 , 35) was investigated to determine if endothelial cells can metabolize a carcinogenic hydrocarbon and if any metabolites formed are proximate carcinogenic forms. To compare BP metabolism in endothelial cells to that in another type of bovine cell and in cells of another species, BP metabolism was also studied in a line of bovine fetal lung fibroblast-like6 cells and in hamster embryo cells.