大鼠肾动脉的缺氧/复氧通过调节非内皮依赖性可溶性鸟苷酸环化酶/环磷酸鸟苷/蛋白激酶G信号传导损害血管舒张功能。
Hypoxia/Reoxygenation of Rat Renal Arteries Impairs Vasorelaxation via Modulation of Endothelium-Independent sGC/cGMP/PKG Signaling.
作者信息
Braun Diana, Zollbrecht Christa, Dietze Stefanie, Schubert Rudolf, Golz Stefan, Summer Holger, Persson Pontus B, Carlström Mattias, Ludwig Marion, Patzak Andreas
机构信息
Renal Vessel Physiology Group, Institute of Vegetative Physiology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
Institute of Vegetative Physiology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
出版信息
Front Physiol. 2018 May 3;9:480. doi: 10.3389/fphys.2018.00480. eCollection 2018.
Ischemia/reperfusion injury holds a key position in many pathological conditions such as acute kidney injury and in the transition to chronic stages of renal damage. We hypothesized that besides a reported disproportional activation of vasoconstrictor response, hypoxia/reoxygenation (H/R) adversely affects endothelial dilatory systems and impairs relaxation in renal arteries. Rat renal interlobar arteries were studied under isometric conditions. Hypoxia was induced by application of 95% N, 5% CO for 60 min to the bath solution, followed by a 10 min period of reoxygenation (95% O, 5% CO). The effect of H/R on relaxation was assessed using various inhibitors of endothelial dilatory systems. mRNA expression of phosphodiesterase 5 (PDE5), NADPH oxidases (NOX), and nitric oxide synthase (NOS) isoforms were determined using qRT-PCR; cGMP was assayed with direct cGMP ELISA. Acetylcholine induced relaxation was impaired after H/R. Inhibition of the NOS isoforms with L-NAME, and cyclooxygenases (COXs) by indomethacin did not abolish the H/R effect. Moreover, blocking the calcium activated potassium channels K and K, the main mediators of the endothelium-derived hyperpolarizing factor, with TRAM34 and UCL1684, respectively, showed similar effects in H/R and control. Arterial stiffness did not differ comparing H/R with controls, indicating no impact of H/R on passive vessel properties. Moreover, superoxide was not responsible for the observed H/R effect. Remarkably, H/R attenuated the endothelium-independent relaxation by sodium nitroprusside, suggesting endothelium-independent mechanisms of H/R action. Investigating the signaling downstream of NO revealed significantly decreased cGMP and impaired relaxation during PDE5 inhibition with sildenafil after H/R. Inhibition of PKG, the target of cGMP, did not normalize SNP-induced relaxation following H/R. However, the soluble guanylyl cyclase (sGC) inhibitor ODQ abolished the H/R effect on relaxation. The mRNA expressions of the endothelial and the inducible NOS were reduced. NOX and PDE5 mRNA were similarly expressed in H/R and control. Our results provide new evidence that impaired renal artery relaxation after H/R is due to a dysregulation of sGC leading to decreased cGMP levels. The presented mechanism might contribute to an insufficient renal reperfusion after ischemia and should be considered in its pathophysiology.
缺血/再灌注损伤在许多病理状况中占据关键地位,如急性肾损伤以及肾损伤向慢性阶段的转变过程。我们推测,除了已报道的血管收缩反应的不成比例激活外,缺氧/复氧(H/R)会对内皮舒张系统产生不利影响,并损害肾动脉的舒张功能。在等长条件下对大鼠肾叶间动脉进行研究。通过向浴液中施加95% N₂、5% CO₂ 60分钟诱导缺氧,随后进行10分钟的复氧(95% O₂、5% CO₂)。使用内皮舒张系统的各种抑制剂评估H/R对舒张的影响。使用qRT-PCR测定磷酸二酯酶5(PDE5)、NADPH氧化酶(NOX)和一氧化氮合酶(NOS)同工型的mRNA表达;用直接cGMP ELISA测定cGMP。H/R后乙酰胆碱诱导的舒张功能受损。用L-NAME抑制NOS同工型以及用吲哚美辛抑制环氧化酶(COXs)并不能消除H/R的影响。此外,分别用TRAM34和UCL1684阻断钙激活钾通道K⁺ 和K⁺(内皮源性超极化因子的主要介质),在H/R组和对照组中显示出相似的效果。比较H/R组和对照组,动脉僵硬度没有差异,表明H/R对血管被动特性没有影响。此外,超氧化物不是观察到的H/R效应的原因。值得注意的是,H/R减弱了硝普钠引起的非内皮依赖性舒张,提示H/R作用的非内皮依赖性机制。研究NO下游信号发现,H/R后用西地那非抑制PDE5期间,cGMP显著降低且舒张功能受损。抑制cGMP的靶标PKG并不能使H/R后SNP诱导的舒张功能恢复正常。然而,可溶性鸟苷酸环化酶(sGC)抑制剂ODQ消除了H/R对舒张的影响。内皮型和诱导型NOS的mRNA表达降低。NOX和PDE5 mRNA在H/R组和对照组中的表达相似。我们的结果提供了新的证据,表明H/R后肾动脉舒张功能受损是由于sGC失调导致cGMP水平降低。所提出的机制可能导致缺血后肾再灌注不足,应在其病理生理学中予以考虑。