Chen X, Catravas J D
Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta 30912.
Am J Physiol. 1993 Sep;265(3 Pt 1):L243-9. doi: 10.1152/ajplung.1993.265.3.L243.
We examined the mechanisms whereby phorbol 12-myristate 13-acetate (PMA)-activated rabbit peritoneal neutrophils [polymorphonuclear leukocytes (PMN)] altered endothelial-bound angiotensin-converting enzyme (ACE) activity in cultured bovine pulmonary arterial endothelial cells (EC). PMA or PMN alone had no effect on ACE activity. When PMN were coincubated with PMA (10 ng/ml) for 4 h in Earle's salt solution, endothelial ACE activity was decreased by 87%. No EC cytotoxicity was observed at this time as determined by 51Cr release from prelabeled EC. Activated PMN-mediated decreased ACE activity was inhibited by catalase (2,000 U/ml) but not by superoxide dismutase (300 U/ml). The decrease in ACE activity was also inhibited by the hydroxyl radical scavenger dimethylthiourea (5 mM) but not mannitol (5 mM), which does not cross cell membranes. Pretreatment of EC with the iron chelator deferoxamine mesylate (1-10 mM) for 4 h attenuated the PMN-mediated decrease in ACE activity, as did the thiol reducing agent, 2-mercaptoethanol (0.1 mM), and the myeloperoxidase inhibitor, cyanide (5 mM), but not azide (1-50 mM). Treatment with the proteinase inhibitor phenylmethylsulfonyl fluoride, with human alpha-antitrypsin, or with the nitric oxide synthase inhibitor N omega-nitro-L-arginine had no effect on PMN-mediated ACE dysfunction. These results suggest that PMN-mediated ACE dysfunction may be due to the production of hydrogen peroxide by PMN and its subsequent conversion into hydroxyl radicals.
我们研究了佛波醇12 - 肉豆蔻酸酯13 - 乙酸酯（PMA）激活的兔腹膜中性粒细胞[多形核白细胞（PMN）]改变培养的牛肺动脉内皮细胞（EC）中内皮结合血管紧张素转换酶（ACE）活性的机制。单独使用PMA或PMN对ACE活性没有影响。当PMN与PMA（10 ng/ml）在Earle盐溶液中共同孵育4小时时，内皮ACE活性降低了87%。此时通过预标记EC的51Cr释放测定未观察到EC细胞毒性。过氧化氢酶（2000 U/ml）可抑制活化的PMN介导的ACE活性降低，但超氧化物歧化酶（300 U/ml）则不能。ACE活性的降低也受到羟基自由基清除剂二甲基硫脲（5 mM）的抑制，但不能穿过细胞膜的甘露醇（5 mM）则无此作用。用铁螯合剂甲磺酸去铁胺（1 - 10 mM）对EC进行4小时预处理可减弱PMN介导的ACE活性降低，硫醇还原剂2 - 巯基乙醇（0.1 mM）和髓过氧化物酶抑制剂氰化物（5 mM）也有此作用，但叠氮化物（1 - 50 mM）则无此作用。用蛋白酶抑制剂苯甲基磺酰氟、人α - 抗胰蛋白酶或一氧化氮合酶抑制剂Nω - 硝基 - L - 精氨酸处理对PMN介导的ACE功能障碍没有影响。这些结果表明，PMN介导的ACE功能障碍可能是由于PMN产生过氧化氢及其随后转化为羟基自由基所致。
