Inducible nitric oxide synthase mediates delayed myocardial protection induced by activation of adenosine A(1) receptors: evidence from gene-knockout mice.
Inducible nitric oxide synthase mediates delayed myocardial protection induced by activation of adenosine A(1) receptors: evidence from gene-knockout mice.
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DOI：
10.1161/01.cir.102.8.902
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发表时间：
2000-08
期刊：
影响因子：
37.8
通讯作者：
Tingcun Zhao;Lei Xi;Jeya Chelliah;Joseph E. Levasseur;R. Kukreja
中科院分区：
文献类型：
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作者：
Tingcun Zhao;Lei Xi;Jeya Chelliah;Joseph E. Levasseur;R. Kukreja
背景由腺苷A(1)受体（A(1)ARs）激活诱导的延迟预适应机制尚不完全清楚。我们利用药物抑制剂和iNOS基因敲除小鼠，确定了诱导型一氧化氮合酶（iNOS）在介导腺苷诱导的晚期心脏保护中的作用。方法与结果用生理盐水或A(1)AR激动剂2-氯- n(6)-环戊基腺苷（CCPA）治疗成年雄性小鼠。24小时后，以Langendorff模式灌注心脏，进行30分钟的全脑缺血和30分钟的再灌注。8-环戊基-1,3-二丙基黄嘌呤（DPCPX, 0.1 mg/kg IP）和s -甲基异硫脲（SMT,3 mg/kg IP）分别阻断A(1)ARs和iNOS。采用三苯四唑氯化染色法检测梗死面积（IS）， Western blots检测iNOS表达。心肌IS由24.0+/-3降低。生理盐水组为2%，ccpa组为12.2+/-2.5% （P<0.05）。CCPA的梗死减少作用被DPCPX（29.3+/-3）所消除。4%)和SMT(32.3+/-2.6%)，而在靶向消融iNOS的小鼠中不存在（23.9+/-1.6%）。CCPA可改善缺血后舒张末压、发育压和率压产物，但DPCPX和SMT也可阻断这一作用。在ccpa处理的心脏中观察到iNOS蛋白表达升高，而DPCPX则降低了iNOS蛋白表达。结论：A(1) ar选择性激活对小鼠缺血/再灌注损伤具有迟发性心脏保护作用。在iNOS基因敲除小鼠中，iNOS表达增加同时缺乏A(1)AR激活的保护作用，表明iNOS在腺苷诱导的晚期心脏保护中存在直接的因果关系。
BACKGROUND The mechanism of delayed preconditioning induced by activation of adenosine A(1) receptors (A(1)ARs) is not fully understood. We determined the role of inducible nitric oxide synthase (iNOS) in mediating adenosine-induced late cardioprotection using pharmacological inhibitors and iNOS gene-knockout mice. METHODS AND RESULTS Adult male mice were treated with saline or an A(1)AR agonist, 2-chloro-N(6)-cyclopentyladenosine (CCPA). Twenty-four hours later, the hearts were perfused in Langendorff mode and subjected to 30 minutes of global ischemia followed by 30 minutes of reperfusion. 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX; 0.1 mg/kg IP) and S-methylisothiourea (SMT; 3 mg/kg IP) were used to block A(1)ARs and iNOS, respectively. Infarct size (IS) was measured by triphenyltetrazolium chloride staining, and iNOS expression was measured by Western blots. Myocardial IS was reduced from 24.0+/-3. 2% in the saline group to 12.2+/-2.5% in CCPA-treated mice (P<0.05). The infarct-reducing effect of CCPA was abrogated by DPCPX (29.3+/-3. 4%) and SMT (32.3+/-2.6%) and was absent in mice with targeted ablation of iNOS (23.9+/-1.6%). CCPA produced improvement in postischemic end-diastolic pressure, developed pressure, and rate-pressure product, which was also blocked by DPCPX and SMT. Increased iNOS protein expression observed in CCPA-treated hearts was diminished by DPCPX. CONCLUSIONS Selective activation of A(1)ARs produces delayed cardioprotection against ischemia/reperfusion injury in the mouse. Increased iNOS expression concomitant with the lack of protective effect of A(1)AR activation in iNOS gene-knockout mice suggests a direct cause-and-effect relationship of iNOS in adenosine-induced late cardioprotection.