P058. Impaired soluble guanylyl cyclase signaling in small mesenteric arteries of angiotensin II-induced hypertensive rats

In cardiovascular disease, oxidative stress can drive soluble guanylyl cyclase (sGC) heme oxidation resulting in the loss of the sGC heme (apo-sGC), the impairment of nitric oxide (NO) binding and cGMP production, and vasoconstriction. Consequently, a new class of therapeutic compounds sGC activators have been developed which target oxidized and apo-sGC to cause irreversible, NO-independent reactivation of cGMP production and vasodilation. While sGC activators have had varied clinical success, surprisingly few studies have defined the impact of NO-independent sGC activation on vascular physiology in healthy conditions. We found mesenteric and pulmonary arteries are two log orders more sensitive to NO-independent sGC activator BAY 58-2667 induced vasodilation than aorta; no difference in NO-dependent sGC vasodilation between vessels was observed. These data indicate the presence of an activatable physiological pool of oxidized and/or apo-sGC in pulmonary and mesenteric arteries. We recently published that smooth muscle cell cytochrome b5 reductase 3 (CYB5R3) acts to reduce oxidized heme sGC back to its NO-sensitive reduced heme state during vascular disease. We found transgenic CYB5R3 overexpression (CYB5R3 OE) mice were more resistant to BAY 58-2667 mesenteric artery vasodilation and blood pressure lowering compared to wild-type controls (n=5-9) under physiologic conditions. Also, healthy CYB5R3 OE pulmonary arteries had a near complete loss of BAY 58-2667 vasodilation suggesting both mesenteric and pulmonary arteries contain a pool of oxidized sGC. We next asked if physiological H 2 O 2 production accounts for changes in BAY 58-2667 responsiveness. We found using mitochondrial-specific catalase overexpression mice, that BAY 58-2667 vasodilation did not differ from controls in any vascular bed (n=4-6). We next tested whether xanthine oxidase (XO), which can produce H 2 O 2 at the endothelial cell surface of vessels, can impact physiological BAY 58-2667 vasodilation. We found that Febuxostat, a XO inhibitor, led to a significant decrease in mesenteric artery BAY 58-2667 induced vasodilation from ~70% to ~30% (n=6). Combined, these data provide evidence for CYB5R3 and XO as regulators of physiological sGC resistance artery vasodilation.

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Mechanisms of nitric oxide-mediated, neurogenic vasodilation in mesenteric resistance arteries of toad Bufo marinus

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00148.2009 ◽

2010 ◽

Vol 298 (3) ◽

pp. R767-R775 ◽

Cited By ~ 10

Author(s):

Brett L. Jennings ◽

John A. Donald

Keyword(s):

Nitric Oxide ◽

Guanylyl Cyclase ◽

Soluble Guanylyl Cyclase ◽

Bufo Marinus ◽

Mesenteric Arteries ◽

Induced Response ◽

Resistance Arteries ◽

Nos Inhibitors ◽

Toad Bufo ◽

Neurogenic Vasodilation

This study determined the role of nitric oxide (NO) in neurogenic vasodilation in mesenteric resistance arteries of the toad Bufo marinus . NO synthase (NOS) was anatomically demonstrated in perivascular nerves, but not in the endothelium. ACh and nicotine caused TTX-sensitive neurogenic vasodilation of mesenteric arteries. The ACh-induced vasodilation was endothelium-independent and was mediated by the NO/soluble guanylyl cyclase signaling pathway, inasmuch as the vasodilation was blocked by the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one and the NOS inhibitors Nω-nitro-l-arginine methyl ester and Nω-nitro-l-arginine. Furthermore, the ACh-induced vasodilation was significantly decreased by the more selective neural NOS inhibitor N5-(1-imino-3-butenyl)-l-ornithine. The nicotine-induced vasodilation was endothelium-independent and mediated by NO and calcitonin gene-related peptide (CGRP), inasmuch as pretreatment of mesenteric arteries with a combination of Nω-nitro-l-arginine and the CGRP receptor antagonist CGRP-(8–37) blocked the vasodilation. Clotrimazole significantly decreased the ACh-induced response, providing evidence that a component of the NO vasodilation involved Ca2+-activated K+ or voltage-gated K+ channels. These data show that NO control of mesenteric resistance arteries of toad is provided by nitrergic nerves, rather than the endothelium, and implicate NO as a potentially important regulator of gut blood flow and peripheral blood pressure.

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Catalase activity and expression are reduced in mesenteric arteries from angiotensin II‐infused hypertensive rats

The FASEB Journal ◽

10.1096/fasebj.21.5.a445-c ◽

2007 ◽

Vol 21 (5) ◽

Author(s):

Kyu‐Tae Kang ◽

Jennifer C. Sullivan ◽

Danielle L. Cruthirds ◽

Jennifer S. Pollock

Keyword(s):

Angiotensin Ii ◽

Catalase Activity ◽

Mesenteric Arteries ◽

Hypertensive Rats

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Soluble guanylyl cyclase is a target of angiotensin II-induced nitrosative stress in a hypertensive rat model

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00138.2012 ◽

2012 ◽

Vol 303 (5) ◽

pp. H597-H604 ◽

Cited By ~ 30

Author(s):

Pierre-Antoine Crassous ◽

Samba Couloubaly ◽

Can Huang ◽

Zongmin Zhou ◽

Padmamalini Baskaran ◽

...

Keyword(s):

Oxidative Stress ◽

Smooth Muscle ◽

Angiotensin Ii ◽

Guanylyl Cyclase ◽

Vascular Reactivity ◽

Nitrosative Stress ◽

Vascular Dysfunction ◽

Soluble Guanylyl Cyclase ◽

Smooth Muscle Relaxation ◽

Ang Ii

Nitric oxide (NO) by activating soluble guanylyl cyclase (sGC) is involved in vascular homeostasis via induction of smooth muscle relaxation. In cardiovascular diseases (CVDs), endothelial dysfunction with altered vascular reactivity is mostly attributed to decreased NO bioavailability via oxidative stress. However, in several studies, relaxation to NO is only partially restored by exogenous NO donors, suggesting sGC impairment. Conflicting results have been reported regarding the nature of this impairment, ranging from decreased expression of one or both subunits of sGC to heme oxidation. We showed that sGC activity is impaired by thiol S-nitrosation. Recently, angiotensin II (ANG II) chronic treatment, which induces hypertension, was shown to generate nitrosative stress in addition to oxidative stress. We hypothesized that S-nitrosation of sGC occurs in ANG II-induced hypertension, thereby leading to desensitization of sGC to NO hence vascular dysfunction. As expected, ANG II infusion increases blood pressure, aorta remodeling, and protein S-nitrosation. Intravital microscopy indicated that cremaster arterioles are resistant to NO-induced vasodilation in vivo in anesthetized ANG II-treated rats. Concomitantly, NO-induced cGMP production decreases, which correlated with S-nitrosation of sGC in hypertensive rats. This study suggests that S-nitrosation of sGC by ANG II contributes to vascular dysfunction. This was confirmed in vitro by using A7r5 smooth muscle cells infected with adenoviruses expressing sGC or cysteine mutants: ANG II decreases NO-stimulated activity in the wild-type but not in one mutant, C516A. This result indicates that cysteine 516 of sGC mediates ANG II-induced desensitization to NO in cells.

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