CHARACTERIZATION OF ENDOTHELIUM-DERIVED HYPERPOLARIZING FACTOR AS A CYTOCHROME P450-DERIVED ARACHIDONIC-ACID METABOLITE IN MAMMALS
CHARACTERIZATION OF ENDOTHELIUM-DERIVED HYPERPOLARIZING FACTOR AS A CYTOCHROME P450-DERIVED ARACHIDONIC-ACID METABOLITE IN MAMMALS
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DOI：
10.1113/jphysiol.1994.sp020449
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发表时间：
1994-12-01
影响因子：
5.5
通讯作者：
BUSSE, R
中科院分区：
文献类型：
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作者：
HECKER, M;BARA, AT;BUSSE, R
1.除了一氧化氮（NO）和前列环素（PGI（2））外，一种尚未鉴定的内皮源性超极化因子（EDHF）也参与了缓激肽在不同血管床中的扩张作用。我们已经研究了该因子在新鲜分离的牛和猪冠状动脉段中的作用的性质和机制，所述冠状动脉段用血栓素模拟物U46619（9，11-双脱氧-11 α，9 α-环氧甲酰基-前列腺素F-2 α，10-30 nM）预收缩。用N-G-硝基-L-精氨酸（L-NNA，30 μ M）抑制NO合成后，缓激肽的浓度-反应曲线显著向右移动，而用双氯芬酸（1 μ M）阻断环加氧酶则没有效果。用氯化钾（40-60 mM）预收缩节段完全消除了对缓激肽的NO/PGI（2）非依赖性扩张反应。在夹心法生物测定实验中，NO的腔内释放和近腔释放都很容易被检测到，但EDHF的释放却很难被检测到.钙激活的钾通道（K-Ca（+））抑制剂，如apamin（1 μ M）和tetrabutylammonium（TBA，3 mM），强烈减弱EDHF介导的缓激肽诱导的舒张，而格列本脲（3 μ M），K-ATP（+）通道抑制剂，没有影响.磷脂酶A（2）抑制剂奎纳克林（30 μ M）和细胞色素P450抑制剂SKF 525 a（30-100 μ M）和克霉唑（100 μ M）也可显著抑制这些舒张作用。此外，与细胞色素P450衍生的花生四烯酸代谢物，11，12-epoxyeicosatetraenoic acid，内皮剥脱的冠状动脉环的孵育，引起浓度依赖性（1-10 μ M）的扩张，这是废除在TBA（3 mM）的存在下和以下预收缩的片段与氯化钾，而不是U46619.5。这些发现表明，缓激肽释放的EDHF是细胞色素P450衍生的花生四烯酸代谢产物，推测是一种环氧化物。该因子似乎通过开放K-Ca（+）通道而使下面的平滑肌细胞层增生。
1. In addition to nitric oxide (NO) and prostacyclin (PGI(2)) an as yet unidentified endothelium-derive hyperpolarizing factor (EDHF) contributes to the dilator effect of bradykinin in different vascular beds. We have investigated the nature and mechanism of action of this factor in freshly isolated bovine and porcine coronary artery segments which were preconstricted with the thromboxane mimetic U46619 (9,11-dideoxy-11 alpha, 9 alpha-epoxymethano-prostaglandin F-2 alpha, 10-30 nM).2. The concentration-response curve of bradykinin was significantly shifted to the right after inhibition of NO synthesis with N-G-nitro-L-arginine (L-NNA, 30 mu M), whereas cyclo-oxygenase blockade with diclofenac (1 mu M) had no effect. Preconstriction of the segments with potassium chloride (40-60 mM) completely abrogated the NO/PGI(2)-independent dilator response to bradykinin. In sandwich bioassay experiments, both the luminal and abluminal release of NO, but not that of EDHF, was readily detectable.3. Inhibitors of Ca2+-activated K+ channels (K-Ca(+)), such as apamin (1 mu M) and tetrabutylammonium (TBA, 3 mM), strongly attenuated the EDHF-mediated bradykinin-induced relaxation, while glibenclamide (3 mu M), an inhibitor of K-ATP(+) channels, had no effect.4. These relaxations were also significantly inhibited by the phospholipase A(2) inhibitor, quinacrine (30 mu M), and the cytochrome P450 inhibitors, SKF525a (30-100 mu M) and clotrimazole (100 mu M). Moreover, incubation of endothelium-denuded coronary artery rings with a cytochrome P450-derived arachidonic acid metabolite, 11,12-epoxyeicosatetraenoic acid, elicited a concentration-dependent (1-10 mu M) dilatation which was abolished both in the presence of TBA (3 mM) and following preconstriction of the segments with potassium chloride instead of U46619.5. These findings suggest that EDHF released by bradykinin is a cytochrome P450-derived arachidonic acid metabolite, presumably an epoxide. This factor seems to hyperpolarize the underlying smooth muscle cell layers by opening K-Ca(+) channels.