Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia.
Am J Physiol Heart Circ Physiol. 2013 Aug 1;305(3):H365-77. doi: 10.1152/ajpheart.00495.2012. Epub 2013 May 31.
Nitroxyl (HNO) is a redox congener of NO. We now directly compare the antihypertrophic efficacy of HNO and NO donors in neonatal rat cardiomyocytes and compare their contributing mechanisms of actions in this setting. Isopropylamine-NONOate (IPA-NO) elicited concentration-dependent inhibition of endothelin-1 (ET1)-induced increases in cardiomyocyte size, with similar suppression of hypertrophic genes. Antihypertrophic IPA-NO actions were significantly attenuated by l-cysteine (HNO scavenger), Rp-8-pCTP-cGMPS (cGMP-dependent protein kinase inhibitor), and 1-H-(1,2,4)-oxodiazolo-quinxaline-1-one [ODQ; to target soluble guanylyl cyclase (sGC)] but were unaffected by carboxy-PTIO (NO scavenger) or CGRP8-37 (calcitonin gene-related peptide antagonist). Furthermore, IPA-NO significantly increased cardiomyocyte cGMP 3.5-fold (an l-cysteine-sensitive effect) and stimulated sGC activity threefold, without detectable NO release. IPA-NO also suppressed ET1-induced cardiomyocyte superoxide generation. The pure NO donor diethylamine-NONOate (DEA-NO) reproduced these IPA-NO actions but was sensitive to carboxy-PTIO rather than l-cysteine. Although IPA-NO stimulation of purified sGC was preserved under pyrogallol oxidant stress (in direct contrast to DEA-NO), cardiomyocyte sGC activity after either donor was attenuated by this stress. Excitingly IPA-NO also exhibited acute antihypertrophic actions in response to pressure overload in the intact heart. Together these data strongly suggest that IPA-NO protection against cardiomyocyte hypertrophy is independent of both NO and CGRP but rather utilizes novel HNO activation of cGMP signaling. Thus HNO acutely limits hypertrophy independently of NO, even under conditions of elevated superoxide. Development of longer-acting HNO donors may thus represent an attractive new strategy for the treatment of cardiac hypertrophy, as stand-alone and/or add-on therapy to standard care.
硝普氢（HNO）是一氧化氮（NO）的氧化还原同系物。我们现在直接比较 HNO 和 NO 供体在新生大鼠心肌细胞中的抗肥厚作用，并比较它们在这种情况下的作用机制。异丙基胺-NONO 酯（IPA-NO）引起内皮素-1（ET1）诱导的心肌细胞大小增加的浓度依赖性抑制，对肥大基因的抑制作用相似。HNO 清除剂 l-半胱氨酸、cGMP 依赖性蛋白激酶抑制剂 Rp-8-pCTP-cGMPS 和可溶性鸟苷酸环化酶（sGC）靶标 1-H-（1,2,4）-恶二唑并喹嗪-1-酮 [ODQ]显著减弱了 IPA-NO 的抗肥厚作用，但不受 NO 清除剂羧基-PTIO 或降钙素基因相关肽拮抗剂 CGRP8-37 的影响。此外，IPA-NO 显著增加心肌细胞 cGMP 3.5 倍（l-半胱氨酸敏感效应）并刺激 sGC 活性三倍，而无可检测的 NO 释放。IPA-NO 还抑制 ET1 诱导的心肌细胞超氧自由基生成。纯 NO 供体二乙胺-NONO 酯（DEA-NO）再现了 IPA-NO 的这些作用，但对羧基-PTIO 敏感而不是 l-半胱氨酸。尽管 IPA-NO 对纯化 sGC 的刺激在焦儿茶酚氧化应激下得以保留（与 DEA-NO 直接相反），但两种供体的心肌细胞 sGC 活性均因这种应激而减弱。令人兴奋的是，IPA-NO 在完整心脏对压力超负荷的急性抗肥厚作用。这些数据强烈表明，IPA-NO 对心肌细胞肥大的保护作用既不依赖于 NO 也不依赖于 CGRP，而是利用新型 HNO 激活 cGMP 信号。因此，HNO 急性地限制肥大，而不依赖于 NO，甚至在超氧自由基升高的情况下也是如此。开发更长作用时间的 HNO 供体可能成为治疗心肌肥大的一种有吸引力的新策略，作为标准治疗的独立或附加治疗。
