Pediatric Heart Lung Center, Sections of Neonatology and Pulmonary Medicine, Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA.
Am J Physiol Lung Cell Mol Physiol. 2011 Nov;301(5):L755-64. doi: 10.1152/ajplung.00138.2010. Epub 2011 Aug 19.
Although inhaled NO (iNO) therapy is often effective in treating infants with persistent pulmonary hypertension of the newborn (PPHN), up to 40% of patients fail to respond, which may be partly due to abnormal expression and function of soluble guanylate cyclase (sGC). To determine whether altered sGC expression or activity due to oxidized sGC contributes to high pulmonary vascular resistance (PVR) and poor NO responsiveness, we studied the effects of cinaciguat (BAY 58-2667), an sGC activator, on pulmonary artery smooth muscle cells (PASMC) from normal fetal sheep and sheep exposed to chronic intrauterine pulmonary hypertension (i.e., PPHN). We found increased sGC α(1)- and β(1)-subunit protein expression but lower basal cGMP levels in PPHN PASMC compared with normal PASMC. To determine the effects of cinaciguat and NO after sGC oxidation in vitro, we measured cGMP production by normal and PPHN PASMC treated with cinaciguat and the NO donor, sodium nitroprusside (SNP), before and after exposure to 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, an sGC oxidizer), hyperoxia (fraction of inspired oxygen 0.50), or hydrogen peroxide (H(2)O(2)). After treatment with ODQ, SNP-induced cGMP generation was markedly reduced but the effects of cinaciguat were increased by 14- and 64-fold in PPHN fetal PASMC, respectively (P < 0.01 vs. controls). Hyperoxia or H(2)O(2) enhanced cGMP production by cinaciguat but not SNP in PASMC. To determine the hemodynamic effects of cinaciguat in vivo, we compared serial responses to cinaciguat and ACh in fetal lambs after ductus arteriosus ligation. In contrast with the impaired vasodilator response to ACh, cinaciguat-induced pulmonary vasodilation was significantly increased. After birth, cinaciguat caused a significantly greater fall in PVR than either 100% oxygen, iNO, or ACh. We conclude that cinaciguat causes more potent pulmonary vasodilation than iNO in experimental PPHN. We speculate that increased NO-insensitive sGC may contribute to the pathogenesis of PPHN, and cinaciguat may provide a novel treatment of severe pulmonary hypertension.
尽管吸入一氧化氮（iNO）治疗通常对治疗新生儿持续性肺动脉高压（PPHN）有效，但多达 40%的患者没有反应，这可能部分是由于可溶性鸟苷酸环化酶（sGC）的异常表达和功能。为了确定由于氧化 sGC 导致的 sGC 表达或活性改变是否导致肺血管阻力（PVR）升高和对 NO 反应性差，我们研究了 sGC 激活剂西那卡塞（BAY 58-2667）对正常胎儿绵羊和暴露于慢性宫内肺动脉高压（即 PPHN）的绵羊肺动脉平滑肌细胞（PASMC）的影响。我们发现与正常 PASMC 相比，PPHN PASMC 中 sGCα（1）-和β（1）-亚基蛋白表达增加，但基础 cGMP 水平降低。为了确定体外 sGC 氧化后西那卡塞和 NO 的作用，我们测量了用西那卡塞和一氧化氮供体硝普钠（SNP）处理的正常和 PPHN PASMC 的 cGMP 产生，然后再将其暴露于 1H-[1,2,4]恶二唑[4,3-a]喹喔啉-1-酮（ODQ，一种 sGC 氧化剂），高氧（吸入氧分数 0.50）或过氧化氢（H（2）O（2））。用 ODQ 处理后，SNP 诱导的 cGMP 生成明显减少，但在 PPHN 胎儿 PASMC 中，西那卡塞的作用分别增加了 14 倍和 64 倍（P<0.01 与对照组相比）。高氧或 H（2）O（2）增强了西那卡塞而不是 SNP 引起的 PASMC 的 cGMP 产生。为了确定西那卡塞在体内的血流动力学效应，我们比较了在动脉导管结扎后胎儿羔羊中西那卡塞和 ACh 的连续反应。与对 ACh 的血管舒张反应受损相反，西那卡塞诱导的肺血管舒张明显增加。出生后，西那卡塞引起的 PVR 下降明显大于 100%氧气、iNO 或 ACh。我们得出结论，西那卡塞在实验性 PPHN 中引起的肺血管舒张作用强于 iNO。我们推测，增加的对 NO 不敏感的 sGC 可能导致 PPHN 的发病机制，西那卡塞可能为严重肺动脉高压提供一种新的治疗方法。
