Endothelial dysfunction in DOCA-salt-hypertensive mice: role of neuronal nitric oxide synthase-derived hydrogen peroxide

Abstract

Endothelial dysfunction is a common problem associated with hypertension and is considered a precursor to the development of micro- and macro-vascular complications. The present study investigated the involvement of nNOS (neuronal nitric oxide synthase) and H2O2 (hydrogen peroxide) in the impaired endothelium-dependent vasodilation of the mesenteric arteries of DOCA (deoxycorticosterone acetate)-salt-hypertensive mice. Myograph studies were used to investigate the endothelium-dependent vasodilator effect of ACh (acetylcholine). The expression and phosphorylation of nNOS and eNOS (endothelial nitric oxide synthase) were studied by Western blot analysis. Immunofluorescence was used to examine the localization of nNOS and eNOS in the endothelial layer of the mesenteric artery. The vasodilator effect of ACh is strongly impaired in mesenteric arteries of DOCA-salt-hypertensive mice. Non-selective inhibition of NOS sharply reduced the effect of ACh in both DOCA-salt-hypertensive and sham mice. Selective inhibition of nNOS and catalase led to a higher reduction in the effect of ACh in sham than in DOCA-salt-hypertensive mice. Production of H2O2 induced by ACh was significantly reduced in vessels from DOCA-salt-hypertensive mice, and it was blunted after nNOS inhibition. The expression of both eNOS and nNOS was considerably lower in DOCA-salt-hypertensive mice, whereas phosphorylation of their inhibitory sites was increased. The presence of nNOS was confirmed in the endothelial layer of mesenteric arteries from both sham and DOCA-salt-hypertensive mice. These results demonstrate that endothelial dysfunction in the mesenteric arteries of DOCA-salt-hypertensive mice is associated with reduced expression and functioning of nNOS and impaired production of nNOS-derived H2O2 Such findings offer a new perspective for the understanding of endothelial dysfunction in hypertension.

Acute inhibition of PMCA4, but not global ablation, reduces blood pressure and arterial contractility via a nNOS‐dependent mechanism

“…nNOS expression and activity have previously been demonstrated in the vasculature including in mesenteric arteries . Previous studies have demonstrated the importance of nNOS on arterial tone, with changes in/ablation of nNOS expression , or with overexpression of PMCA4 as a regulator of nNOS activity or in disease states such as hypertension . In contrast, we found no significant effect of inhibition of nNOS with VLN or NOS with LNNA alone on BP or on arterial contractility, respectively.…”

“…In WT mice, we showed that the effects of acute PMCA4 inhibition with ATA on BP and isolated arterial contractility were not observed in the presence of inhibitors of nNOS, suggesting these effects of ATA are also via a nNOS-dependent mechanism(s). nNOS expression and activity have previously been demonstrated in the vasculature including in mesenteric arteries [17,[42][43][44][45]. Previous studies have demonstrated the importance of nNOS on arterial tone, with changes in/ablation of nNOS expression [14], or with overexpression of PMCA4 as a regulator of nNOS activity [17] or in disease states such as hypertension [42,45].…”

Flow does not alter eNOS phosphoryation at Ser1179 or Thr495 in preconstricted mouse mesenteric arteries

“…; Silva et al. ), and iNOS can be induced in endothelium with knock‐out of the other NOS isoforms (Takaki et al. ).…”

Vascular Kinin B1 and B2 Receptors Determine Endothelial Dysfunction through Neuronal Nitric Oxide Synthase

“…Indeed, the oxidative stress is the major cause of endothelial dysfunction in several forms of vascular diseases, mainly via disruption of NO· signaling pathway (Drummond et al, 2011; Silva et al, 2016). Therefore, enhanced superoxide anion dismutation through the SOD mimetic can prevents the inactivation of NO· and formation of the highly reactive intermediate peroxynitrite (Weaver et al, 2005), and thus yielding augmented H 2 O 2 concentration, an endothelium-dependent relaxing factor in aorta (Capettini et al, 2008, 2010).…”

“…nNOS uncoupling has been implicated in several endothelium-dependent vascular disorders such as, in mesenteric artery of DOCA-salt hypertensive mice (Silva et al, 2016), thoracic aorta subjected to experimental atherosclerosis model (Capettini et al, 2011) and penile arteries of obese Zucker rat (Sánchez et al, 2012). Accordingly, deficient mice of B 1 -kinin receptor has been described to aggravate atherosclerosis and the development of abdominal aorta aneurysms in ApoE −/− mice under cholesterol rich-diet (Merino et al, 2009).…”