Nitric Oxide- and Heme-Independent Activation of Soluble Guanylate Cyclase Attenuates Peroxynitrite-Induced Endothelial Dysfunction in Rat Aorta

Abstract

Oxidative stress interferes with nitric oxide (NO)/soluble guanylate cyclase (sGC)/cyclic guanosine monophosphate (cGMP) signalling pathway through reduction of endogenous NO and formation of the strong intermediate oxidant peroxynitrite and leads to vascular dysfunction. We evaluated the effects of oral treatment with NO- and heme-independent sGC activator cinaciguat on peroxynitrite-induced vascular dysfunction in rat aorta. Sprague-Dawley rats were treated orally 2 times at an interval of 17 hours with vehicle or with cinaciguat (10 mg/kg). One hour after the last treatment, the animals were anesthetized, the thoracic aorta was removed, and the aortic segment preparations were incubated with and without the reactive oxidant peroxynitrite (200 µmol/L, 30 minutes). Endothelium-dependent (acetylcholine), -independent (sodium nitroprusside) vasorelaxations were investigated, and histopathological examination was performed. Incubation of aortic rings with peroxynitrite significantly attenuated the maximal endothelium-dependent relaxation (R (max)) to acetylcholine (peroxynitrite, 44.5% ± 5.9% vs control, 93.2% ± 2.0%, P < .05) and decreased pD(2) values (-logEC(50), EC(50) being the concentration of acetylcholine that elicited 50% of the maximal response) for the concentration-response curves as compared to control segments. Treatment of rats with cinaciguat significantly improved the decreased acetylcholine-induced vasorelaxation after exposure of aortic rings to peroxynitrite (cinaciguat + peroxynitrite, 67.1% ± 3.5% vs peroxynitrite, 44.5% ± 5.9%, P < .05). Incubation of aortic segments with peroxynitrite caused a significant shift of the sodium nitroprusside concentration-response curves to the right without any alterations in the R (max). Moreover, exposure of aortic rings to peroxynitrite resulted in increased nitro-oxidative stress and DNA breakage which were improved by cinaciguat. Treatment of rats with cinaciguat significantly increased intracellular cGMP levels in the aortic wall. Our results show under conditions of nitro-oxidative stress when signalling in the NO/sGC/cGMP pathway is impaired, acute activation of sGC by cinaciguat might be advantageous in the treatment of endothelial dysfunction in cardiovascular disease.

Effects of Peroxynitrite on Relaxation through the NO/sGC/cGMP Pathway in Isolated Rat Iliac Arteries

“…In fact, exposure to peroxynitrite decreased the relaxant potency and efficacy of either nitroglycerin or acidified NaNO 2 in endothelium-denuded rat iliac arteries. Similar effects of peroxynitrite on an NO donor-induced vasorelaxation have been reported by a number of investigators [8,18,19]. Since the impairment by peroxynitrite of NO-mediated relaxation in the present study was also observed in the presence of SOD or tempol, a causal mediator responsible for this seems to be peroxynitrite itself.…”

“…The heme iron of sGC is no exception either, because spectroelectrochemical analysis has demonstrated that peroxynitrite readily oxidizes the ferrous heme iron of sGC to the ferric state [17]. In this regard, an impaired and augmented effect of peroxynitrite on the relaxant response to an NO donor [8,18,19] and an sGC activator [8], respectively, has been reported. However, it is not entirely clear how peroxynitrite modulates the NO/sGC/cGMP pathway, especially the sGC redox equilibrium, in the vasculature.…”

Regulation of Cellular Communication by Signaling Microdomains in the Blood Vessel Wall

“…Since then, a number of intra-and intercellular targets for bioactive NO have been identified with the biological effects ranging from enzyme activation or inhibition, posttranslational modifications altering protein function, including S-nitrosylation and tyrosine nitrosation, and the generation of complex reactive nitrogen and oxygen species through the rapid spontaneous reaction of NO with other gaseous molecules in the cell (Ignarro, 1991;Davidge et al, 1995;Xu et al, 1998;Handy and Loscalzo, 2006;Yoshida et al, 2006;Kang-Decker et al, 2007;Selemidis et al, 2007;Zuckerbraun et al, 2007;Illi et al, 2008;Briones et al, 2009;Fernhoff et al, 2009;Lima et al, 2010;Thibeault et al, 2010;Bess et al, 2011;Choi et al, 2011;Straub et al, 2011;Marin et al, 2012;Haldar and Stamler, 2013;Korkmaz et al, 2013).…”

A szolubilis guanilát-cikláz aktivátor cinaciguat megelőzi a kardiális diszfunkció kialakulását 1-es típusú cukorbetegség patkánymodelljében

“…Irodalmi adatok szerint az sGC aktivátor cinaciguat (BAY 58-2667) az sGC NO-ra érzéketlen formájának hemkötő zsebéhez kapcsolódik, így helyreállítja annak cGMP-termelését (15). Újabb tanulmányok a cinaciguat jótékony hatását bizonyították miokardiális infarktus (16), miokardiális iszkémiás-reperfúziós károsodás modelljeiben (17, 18), nitro-oxidatív stressz által indukált endothelialis diszfunkcióban (19), vaszkuláris neointima-képződés esetén (20) és a patológiás szívizom-hipertrófi a megelő-zésében (21). A cinaciguat biztonságosságát és tolerálhatóságát humán klinikai vizsgálatokban (fázis I.)…”