Granberg A L, Brunström B, Brandt I
Department of Environmental Toxicology, Evolutionary Biology Centre, Uppsala University, Sweden.
Arch Toxicol. 2000 Dec;74(10):593-601. doi: 10.1007/s002040000171.
Autoradiography was used to investigate the cellular sites of irreversible binding of 3H-labelled 7,12-dimethylbenz[a]anthracene (DMBA) and benzo[a]pyrene (B[a]P) in mice. Autoradiograms obtained from solvent-extracted tape-sections revealed an even distribution of DMBA- and B[a]P-derived radioactivity in control mice lacking sites of selective binding in the tissues. In mice pretreated with a cytochrome P4501A (CYP1A) inducer, beta-naphthoflavone (BNF) or 3,3',4,4', 5-pentachlorobiphenyl (PCB 126), a noticeable accumulation of bound radioactivity was observed in the pulmonary alveolar region. Increased labelling was also observed in heart tissue of induced mice. As demonstrated by microautoradiography of tissues from CYP1A-induced mice treated with 3H-DMBA or 3H-B[a]P in vivo, irreversible binding in lung tissue was present in endothelial cells of arteries and veins, in the alveolar septal walls, and in type 2 pneumocytes. In heart tissue, binding was confined to endothelial cells of arteries, capillaries and veins. In liver, binding was found in the hepatocytes as well as in endothelial cells of the portal veins, whereas no binding was seen in endothelial cells of the sinusoids, central veins, or arteries. These findings were confirmed in vitro using 3H-DMBA-exposed precision-cut slices, indicating that reactive intermediates of DMBA and B(a)P were formed in situ. The addition of the CYP1A inhibitor ellipticine abolished binding in the target endothelial cells. Increased endothelial binding in the lungs and liver of CYP1A-induced mice was concomitant with increased 7-ethoxyresorufin O-deethylase (EROD) and DMBA hydroxylase activity. In heart, endothelial binding was positively correlated with EROD, but not with DMBA hydroxylase. The results suggest that endothelial cells may be targets for CYP-dependent activation of such toxicants as polycyclic aromatic hydrocarbons. Consequently, the possibility that chemically induced endothelial dysfunction is a risk factor in the aetiology of cardiovascular disease demands consideration.
利用放射自显影技术研究了3H标记的7,12-二甲基苯并[a]蒽（DMBA）和苯并[a]芘（B[a]P）在小鼠体内不可逆结合的细胞位点。从溶剂萃取的胶带切片获得的放射自显影片显示，在组织中缺乏选择性结合位点的对照小鼠中，DMBA和B[a]P衍生的放射性呈均匀分布。在用细胞色素P4501A（CYP1A）诱导剂β-萘黄酮（BNF）或3,3',4,4',5-五氯联苯（PCB 126）预处理的小鼠中，在肺泡区域观察到结合放射性的明显积累。在诱导小鼠的心脏组织中也观察到标记增加。如通过对体内用3H-DMBA或3H-B[a]P处理的CYP1A诱导小鼠的组织进行显微放射自显影所示，肺组织中的不可逆结合存在于动脉和静脉的内皮细胞、肺泡间隔壁以及II型肺细胞中。在心脏组织中，结合局限于动脉、毛细血管和静脉的内皮细胞。在肝脏中，结合见于肝细胞以及门静脉的内皮细胞，而在肝血窦、中央静脉或动脉的内皮细胞中未见结合。使用暴露于3H-DMBA的精密切片在体外证实了这些发现，表明DMBA和B(a)P的反应性中间体在原位形成。添加CYP1A抑制剂玫瑰树碱消除了靶内皮细胞中的结合。CYP1A诱导小鼠的肺和肝脏中内皮结合增加与7-乙氧基异吩恶唑酮O-脱乙基酶（EROD）和DMBA羟化酶活性增加同时发生。在心脏中，内皮结合与EROD呈正相关，但与DMBA羟化酶无关。结果表明，内皮细胞可能是多环芳烃等毒物的CYP依赖性激活的靶标。因此，化学诱导的内皮功能障碍是心血管疾病病因中的一个危险因素这一可能性值得考虑。
