García-Redondo Ana Belén, Briones Ana María, Beltrán Amada Elia, Alonso María Jesús, Simonsen Ulf, Salaices Mercedes
Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo 4, 28029 Madrid, Spain.
J Pharmacol Exp Ther. 2009 Jan;328(1):19-27. doi: 10.1124/jpet.108.144295. Epub 2008 Sep 25.
This study investigated the mechanisms underlying the response to hydrogen peroxide (H(2)O(2)) in mesenteric resistance arteries from spontaneously hypertensive rats (SHRs) and normotensive Wistar Kyoto (WKY) rats. Arteries were mounted in microvascular myographs for isometric tension recording and for simultaneous measurements of intracellular Ca(2+) concentration (Ca(2+)), superoxide anion (O(2)(.)) production was evaluated by dihydroethidium fluorescence and confocal microscopy, and thromboxane A(2) (TXA(2)) production was evaluated by enzyme immunoassay. H(2)O(2) (1-100 microM) induced biphasic responses characterized by a transient endothelium-dependent contraction followed by relaxation. Simultaneous measurements of tension and Ca(2+) showed a greater effect of H(2)O(2) in arteries from hypertensive than normotensive rats. The cyclooxygenase (cox) inhibitor, indomethacin [1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1-H-indole-3-acetic acid] (1 microM); the COX-1 inhibitor, SC-58560 [5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethyl pyrazole] (1 microM); the thromboxane (TXA(2)) synthase inhibitor, furegrelate [5-(3-pyridinylmethyl)-2-benzofurancarboxylic acid, sodium salt] (10 microM); and the TXA(2)/prostaglandin H(2) receptor antagonist, SQ 29,548 ([1S-[1.alpha.,2.alpha.(Z),3.alpha.,4.alpha.]]-7-[3-[[2-[(phenylamino) carbonyl] hydrazino] methyl]-7-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid)) (1 microM) abolished H(2)O(2) contraction in arteries from WKY rats but only reduced it in SHRs. The O(2)(.) scavenger, tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt) (1 mM), and the NADPH oxidase inhibitor, apocynin (4'-hydroxy-3'-methoxyacetophenone) (0.3 mM), decreased H(2)O(2) contraction in arteries from SHRs but not in WKY rats. H(2)O(2) induced TXA(2) and O(2)(.) production that was greater in SHRs than in WKY rats. The TXA(2) analog, U46619 [9,11-di-deoxy-11 alpha,9 alpha-epoxymethano prostaglandin F(2 alpha) (0.1 nM-1 microM)], also increased O(2)(.) production in SHR vessels. H(2)O(2)-induced TXA(2) production was decreased by SC-58560. H(2)O(2)-induced O(2)(.) production was decreased by tiron, apocynin, and SQ 29,548. In conclusion, the enhanced H(2)O(2) contraction in resistance arteries from SHRs seems to be mediated by increased TXA(2) release from COX-1 followed by elevations in vascular smooth muscle Ca(2+) levels and O(2)(.) production. This reveals a new mechanism of oxidative stress-induced vascular damage in hypertension.
本研究调查了自发性高血压大鼠（SHR）和正常血压的Wistar Kyoto（WKY）大鼠肠系膜阻力动脉对过氧化氢（H₂O₂）反应的潜在机制。将动脉安装在微血管肌动描记器上以记录等长张力，并同时测量细胞内Ca²⁺浓度（[Ca²⁺]i），通过二氢乙锭荧光和共聚焦显微镜评估超氧阴离子（O₂⁻）的产生，通过酶免疫测定评估血栓素A₂（TXA₂）的产生。H₂O₂（1 - 100 μM）诱导双相反应，其特征是短暂的内皮依赖性收缩，随后是舒张。张力和Ca²⁺的同步测量显示，H₂O₂对高血压大鼠动脉的作用大于正常血压大鼠。环氧化酶（COX）抑制剂吲哚美辛[1 - （4 - 氯苯甲酰基）- 5 - 甲氧基 - 2 - 甲基 - 1 - H - 吲哚 - 3 - 乙酸]（1 μM）；COX - 1抑制剂SC - 58560 [5 - （4 - 氯苯基）- 1 - （4 - 甲氧基苯基）- 3 - 三氟甲基吡唑]（1 μM）；血栓素（TXA₂）合酶抑制剂呋格雷酯[5 - （3 - 吡啶基甲基）- 2 - 苯并呋喃羧酸，钠盐]（10 μM）；以及TXA₂/前列腺素H₂受体拮抗剂SQ 29548（[1S - [1α，2α（Z），3α，4α]] - 7 - [3 - [[2 - [（苯基氨基）羰基]肼基]甲基] - 7 - 氧杂双环[2.2.1]庚 - 2 - 基] - 5 - 庚烯酸）（1 μM）可消除WKY大鼠动脉中H₂O₂诱导的收缩，但仅降低SHR中的收缩。O₂⁻清除剂钛铁试剂（4,5 - 二羟基 - 1,3 - 苯二磺酸二钠盐）（1 mM）和NADPH氧化酶抑制剂夹竹桃麻素（4'-羟基 - 3'-甲氧基苯乙酮）（0.3 mM）可降低SHR动脉中H₂O₂诱导的收缩，但对WKY大鼠动脉无此作用。H₂O₂诱导的TXA₂和O₂⁻产生在SHR中比在WKY大鼠中更大。TXA₂类似物U46619 [9,11 - 二脱氧 - 11α，9α - 环氧甲撑前列腺素F₂α（0.1 nM - 1 μM）]也增加了SHR血管中O₂⁻的产生。SC - 58560可降低H₂O₂诱导的TXA₂产生。钛铁试剂、夹竹桃麻素和SQ 29,548可降低H₂O₂诱导的O₂⁻产生。总之，SHR阻力动脉中增强的H₂O₂收缩似乎是由COX - 1释放的TXA₂增加介导的，随后血管平滑肌[Ca²⁺]i水平升高和O₂⁻产生增加。这揭示了高血压中氧化应激诱导血管损伤的新机制。
