Department of Structural and Functional Biology, Institute of Biology, University of Campinas - UNICAMP, Campinas, SP, Brazil.
Department of Structural and Functional Biology, Institute of Biology, University of Campinas - UNICAMP, Campinas, SP, Brazil.
Life Sci. 2015 Mar 15;125:49-56. doi: 10.1016/j.lfs.2015.01.018. Epub 2015 Jan 29.
The aim of this study was to investigate whether β-adrenoceptor (β-AR) overstimulation induced by in vivo treatment with isoproterenol (ISO) alters vascular reactivity and nitric oxide (NO) production and signaling in pulmonary arteries.
Vehicle or ISO (0.3mgkg(-1)day(-1)) was administered daily to male Wistar rats. After 7days, the jugular vein was cannulated to assess right ventricular (RV) systolic pressure (SP) and end diastolic pressure (EDP). The extralobar pulmonary arteries were isolated to evaluate the relaxation responses, protein expression (Western blot), NO production (diaminofluorescein-2 fluorescence), and cyclic guanosine 3',5'-monophosphate (cGMP) levels (enzyme immunoassay kit).
ISO treatment induced RV hypertrophy; however, no differences in RV-SP and EDP were observed. The pulmonary arteries from the ISO-treated group showed enhanced relaxation to acetylcholine that was abolished by the NO synthase (NOS) inhibitor N(ω)-nitro-l-arginine methyl ester (l-NAME); whereas relaxation elicited by sodium nitroprusside, ISO, metaproterenol, mirabegron, or KCl was not affected by ISO treatment. ISO-treated rats displayed enhanced endothelial NOS (eNOS) and vasodilator-stimulated phosphoprotein (VASP) expression in the pulmonary arteries, while phosphodiesterase-5 protein expression decreased. ISO treatment increased NO and cGMP levels and did not induce eNOS uncoupling.
The present data indicate that β-AR overactivation enhances the endothelium-dependent relaxation of pulmonary arteries. This effect was linked to an increase in eNOS-derived NO production, cGMP formation and VASP content and to a decrease in phosphodiesterase-5 expression. Therefore, elevated NO bioactivity through cGMP/VASP signaling could represent a protective mechanism of β-AR overactivation on pulmonary circulation.
本研究旨在探讨体内给予异丙肾上腺素（ISO）治疗是否会改变肺动脉的血管反应性和一氧化氮（NO）产生和信号转导。
雄性 Wistar 大鼠每日给予载体或 ISO（0.3mgkg(-1)day(-1)）。7 天后，颈静脉插管评估右心室（RV）收缩压（SP）和舒张末期压（EDP）。分离肺外叶肺动脉，评估舒张反应、蛋白表达（Western blot）、NO 产生（二氨基荧光素-2 荧光）和环鸟苷 3',5'-单磷酸（cGMP）水平（酶免疫测定试剂盒）。
ISO 处理诱导 RV 肥大；然而，RV-SP 和 EDP 没有差异。来自 ISO 处理组的肺动脉对乙酰胆碱的舒张反应增强，该反应被一氧化氮合酶（NOS）抑制剂 N(ω)-硝基-l-精氨酸甲酯（l-NAME）消除；而 ISO 处理对硝普钠、ISO、间羟舒喘灵、米拉贝隆或 KCl 引起的舒张反应没有影响。ISO 处理大鼠肺动脉内皮型一氧化氮合酶（eNOS）和血管扩张刺激磷酸蛋白（VASP）表达增强，而磷酸二酯酶-5 蛋白表达降低。ISO 处理增加了 NO 和 cGMP 水平，没有诱导 eNOS 解偶联。
本研究数据表明，β-AR 过度激活增强了肺动脉的内皮依赖性舒张。这种作用与 eNOS 衍生的 NO 产生、cGMP 形成和 VASP 含量增加以及磷酸二酯酶-5 表达降低有关。因此，通过 cGMP/VASP 信号转导增加 NO 生物活性可能代表了β-AR 过度激活对肺循环的保护机制。
