Vasodilator responses to acetylcholine are not mediated by the activation of soluble guanylate cyclase or TRPV4 channels in the rat

The effects of 1H-[1,2,4]-oxadizaolo[4,3-]quinoxaline-1-one (ODQ), an inhibitor of the activation of soluble guanylate cyclase (sGC) on responses to NO donors acetylcholine (ACh) and bradykinin (BK) were investigated in the pulmonary and systemic vascular beds of the rat. In these studies the administration of ODQ in a dose of 5 mg/kg iv attenuated vasodilator responses to five different NO donors without inhibiting responses to ACh and BK in the systemic and pulmonary vascular beds of the rat. Vasodilator responses to ACh were not inhibited by l-NAME or the transient receptor vanilloid type 4 (TRPV4) antagonist GSK-2193874, which attenuated vasodilator responses to the TRPV4 agonist GSK-1016790A. ODQ did not inhibit vasodilator responses to agents reported to act in an NO-independent manner or to vasoconstrictor agents, and ODQ did not increase blood methemoglobin levels, suggesting that off target effects were minimal. These results show that ODQ in a dose that inhibited NO donor-mediated responses did not alter vasodilator responses to ACh in the pulmonary and systemic vascular beds and did not alter systemic vasodilator responses to BK. The present results indicate that decreases in pulmonary and systemic arterial pressures in response to ACh are not mediated by the activation of sGC or TRPV4 channels and that ODQ can be used to study the role of the activation of sGC in mediating vasodilator responses in the rat.

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Effects of nitroglycerin/L-cysteine on soluble guanylate cyclase: evidence for an activation/inactivation equilibrium controlled by nitric oxide binding and haem oxidation

Biochemical Journal ◽

10.1042/bj20050565 ◽

2005 ◽

Vol 390 (2) ◽

pp. 625-631 ◽

Cited By ~ 14

Author(s):

Antonius C. F. Gorren ◽

Michael Russwurm ◽

Alexander Kollau ◽

Doris Koesling ◽

Kurt Schmidt ◽

...

Keyword(s):

Nitric Oxide ◽

Guanylate Cyclase ◽

Soluble Guanylate Cyclase ◽

Soret Band ◽

Flavin Mononucleotide ◽

Independent Manner ◽

No Donor ◽

No Release ◽

Glycerol Trinitrate ◽

Haem Protein

GTN (nitroglycerin; glycerol trinitrate) causes dilation of blood vessels via activation of nitric oxide (NO)-sensitive sGC (soluble guanylate cyclase), a heterodimeric haem protein that catalyses the conversion of GTP into cGMP. Activation of sGC by GTN requires enzymatic or non-enzymatic bioactivation of the nitrate. Based on insufficient NO release and lack of spectroscopic evidence for formation of NO–sGC, the cysteine (Cys)-dependent activation of sGC by GTN was proposed to occur in an NO-independent manner. This extraordinary claim is questioned by the present findings. First, the effect of GTN/Cys was blocked by the NO scavenger oxyhaemoglobin, the superoxide-generating compound flavin mononucleotide and the haem-site sGC inhibitor ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one). Secondly, at equi-effective concentrations, GTN/Cys and the NO donor 2,2-diethyl-1-nitroso-oxyhydrazine released identical amounts of NO. Finally, at sufficiently high rates of NO release, activation of sGC by GTN/Cys was accompanied by a shift of the Soret band from 431 to 399 nm, indicating formation of NO–sGC. In the absence of Cys, GTN caused haem oxidation, apparent as a shift of the Soret band to 392 nm, which was accompanied by inactivation of the NO-stimulated enzyme. These results suggest that the effect of GTN/Cys is the result of an activation/inactivation equilibrium that is controlled by the rate of NO release and haem oxidation.

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The role of nitric oxide in the regulation of the electrical activity of the trigeminal nerve in the rat

10.34014/mpphe.2021-177-180 ◽

2021 ◽

Author(s):

S.O. Svitko ◽

K.S. Koroleva ◽

G.F. Sitdikova ◽

K.A. Petrova

Keyword(s):

Nitric Oxide ◽

Sodium Nitroprusside ◽

Trigeminal Nerve ◽

Guanylate Cyclase ◽

Soluble Guanylate Cyclase ◽

No Synthase ◽

The Body ◽

No Donor ◽

No Signaling

Nitric oxide (NO) is a gaseous signaling molecule that regulates a number of physiological functions, including its role in the formation of migraine has been established. NO is endogenously produced in the body from L-arginine by NO synthase. The NO donor, nitroglycerin, is a trigger of migraine in humans and is widely used in the modeling of this disease in animals, which suggests the involvement of components of the NO signaling cascade in the pathogenesis of migraine. Based on the results obtained, it was found that an increase in the concentration of both the substrate for the synthesis of NO, L-arginine, and the NO donor, sodium nitroprusside, has a pro-nociceptive effect in the afferents of the trigeminal nerve. In this case, the effect of sodium nitroprusside is associated with the activation of intracellular soluble guanylate cyclase. Key words: nitric oxide, migraine, trigeminal nerve, L-arginine, guanylate cyclase, sodium nitroprusside, nociception.

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Downregulation of Soluble Guanylate Cyclase and Protein Kinase G With Upregulated ROCK2 in the Pulmonary Artery Leads to Thromboxane A2 Sensitization in Monocrotaline-Induced Pulmonary Hypertensive Rats

Frontiers in Physiology ◽

10.3389/fphys.2021.624967 ◽

2021 ◽

Vol 12 ◽

Author(s):

Suhan Cho ◽

Hyun Namgoong ◽

Hae Jin Kim ◽

Rany Vorn ◽

Hae Young Yoo ◽

...

Keyword(s):

Pulmonary Artery ◽

Guanylate Cyclase ◽

Soluble Guanylate Cyclase ◽

Thromboxane A2 ◽

Immunoblot Analysis ◽

No Donor ◽

Cgmp Signaling ◽

Cgmp Analog ◽

Pulmonary Arterial

Thromboxane A2 (TXA2) promotes various physiological responses including pulmonary artery (PA) contraction, and pathophysiological implications have been suggested in cardiovascular diseases including pulmonary hypertension. Here, we investigated the role of TXA2 receptor (TP)-mediated signaling in the pathophysiology of pulmonary arterial hypertension (PAH). The sensitivity of PA to the contractile agonist could be set by relaxing signals such as the nitric oxide (NO), soluble guanylate cyclase (sGC), and cGMP-dependent kinase (PKG) pathways. Changes in the TP agonist (U46619)-induced PA contraction and its modulation by NO/cGMP signaling were analyzed in a monocrotaline-induced PAH rat model (PAH-MCT). In the myograph study, PA from PAH-MCT showed higher responsiveness to U46619, that is decreased EC50. Immunoblot analysis revealed a lower expression of eNOS, sGC, and PKG, while there was a higher expression of RhoA-dependent kinase 2 (ROCK2) in the PA from PAH-MCT than in the control. In PAH-MCT, the higher sensitivity to U46619 was reversed by 8-Br-cGMP, a membrane-permeable cGMP analog, but not by the NO donor, sodium nitroprusside (SNP 30 μM). In contrast, in the control PA, inhibition of sGC by its inhibitor (1H− [1,2,4] oxadiazolo [4,3−a] quinoxalin-1-one (ODQ), 10 μM) lowered the threshold of U46619-induced contraction. In the presence of ODQ, SNP treatment had no effect whereas the addition of 8-Br-cGMP lowered the sensitivity to U46619. The inhibition of ROCK by Y-27632 attenuated the sensitivity to U46619 in both control and PAH-MCT. The study suggests that the attenuation of NO/cGMP signaling and the upregulation of ROCK2 increase the sensitivity to TXA2 in the PAH animal, which might have pathophysiological implications in patients with PAH.

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Current Modulation of Guanylate Cyclase Pathway Activity—Mechanism and Clinical Implications

Molecules ◽

10.3390/molecules26113418 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3418

Author(s):

Grzegorz Grześk ◽

Alicja Nowaczyk

Keyword(s):

Guanylate Cyclase ◽

Natriuretic Peptides ◽

Soluble Guanylate Cyclase ◽

Cyclic Guanosine Monophosphate ◽

Guanosine Monophosphate ◽

Pharmacological Intervention ◽

First Line ◽

Phosphodiesterase Type ◽

Activity Mechanism

For years, guanylate cyclase seemed to be homogenic and tissue nonspecific enzyme; however, in the last few years, in light of preclinical and clinical trials, it became an interesting target for pharmacological intervention. There are several possible options leading to an increase in cyclic guanosine monophosphate concentrations. The first one is related to the uses of analogues of natriuretic peptides. The second is related to increasing levels of natriuretic peptides by the inhibition of degradation. The third leads to an increase in cyclic guanosine monophosphate concentration by the inhibition of its degradation by the inhibition of phosphodiesterase type 5. The last option involves increasing the concentration of cyclic guanosine monophosphate by the additional direct activation of soluble guanylate cyclase. Treatment based on the modulation of guanylate cyclase function is one of the most promising technologies in pharmacology. Pharmacological intervention is stable, effective and safe. Especially interesting is the role of stimulators and activators of soluble guanylate cyclase, which are able to increase the enzymatic activity to generate cyclic guanosine monophosphate independently of nitric oxide. Moreover, most of these agents are effective in chronic treatment in heart failure patients and pulmonary hypertension, and have potential to be a first line option.

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Role of soluble guanylate cyclase in progressive renal fibrosis

BMC Pharmacology ◽

10.1186/1471-2210-5-s1-s32 ◽

2005 ◽

Vol 5 (Suppl 1) ◽

pp. S32

Author(s):

Harm Peters

Keyword(s):

Guanylate Cyclase ◽

Renal Fibrosis ◽

Soluble Guanylate Cyclase

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Protoporphyrin IX generation from δ-aminolevulinic acid elicits pulmonary artery relaxation and soluble guanylate cyclase activation

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00482.2005 ◽

2006 ◽

Vol 291 (3) ◽

pp. L337-L344 ◽

Cited By ~ 22

Author(s):

Christopher J. Mingone ◽

Sachin A. Gupte ◽

Joseph L. Chow ◽

Mansoor Ahmad ◽

Nader G. Abraham ◽

...

Keyword(s):

Guanylate Cyclase ◽

Vascular Function ◽

Soluble Guanylate Cyclase ◽

Aminolevulinic Acid ◽

Pulmonary Arteries ◽

Protoporphyrin Ix ◽

Physiological Mechanism ◽

No Donor ◽

Vasp Phosphorylation ◽

Guanylate Cyclase Activation

Protoporphyrin IX is an activator of soluble guanylate cyclase (sGC), but its role as an endogenous regulator of vascular function through cGMP has not been previously reported. In this study we examined whether the heme precursor δ-aminolevulinic acid (ALA) could regulate vascular force through promoting protoporphyrin IX-elicited activation of sGC. Exposure of endothelium-denuded bovine pulmonary arteries (BPA) in organoid culture to increasing concentrations of the heme precursor ALA caused a concentration-dependent increase in BPA epifluorescence, consistent with increased tissue protoporphyrin IX levels, associated with decreased force generation to increasing concentrations of serotonin. The force-depressing actions of 0.1 mM ALA were associated with increased cGMP-associated vasodilator-stimulated phosphoprotein (VASP) phosphorylation and increased sGC activity in homogenates of BPA cultured with ALA. Increasing iron availability with 0.1 mM FeSO4 inhibited the decrease in contraction to serotonin and increase in sGC activity caused by ALA, associated with decreased protoporphyrin IX and increased heme. Chelating endogenous iron with 0.1 mM deferoxamine increased the detection of protoporphyrin IX and force depressing activity of 10 μM ALA. The inhibition of sGC activation with the heme oxidant 10 μM 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) attenuated the force depressing actions of an NO donor without altering the actions of ALA. Thus control of endogenous formation of protoporphyrin IX from ALA by the availability of iron is potentially a novel physiological mechanism of controlling vascular function through regulating the activity of sGC.

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Nitric oxide decreases endothelin-1 secretion through the activation of soluble guanylate cyclase

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00224.2003 ◽

2004 ◽

Vol 286 (5) ◽

pp. L984-L991 ◽

Cited By ~ 57

Author(s):

Lisa K. Kelly ◽

Stephen Wedgwood ◽

Robin H. Steinhorn ◽

Stephen M. Black

Keyword(s):

Nitric Oxide ◽

Guanylate Cyclase ◽

Soluble Guanylate Cyclase ◽

Primary Cultures ◽

No Donor ◽

Endothelin 1 ◽

Cgmp Analog ◽

Pulmonary Arterial ◽

Long Acting ◽

Arterial Endothelial Cells

The use of exogenous nitric oxide (NO) has been shown to alter the regulation of other endothelially derived mediators of vascular tone, such as endothelin-1 (ET-1). However, the interaction between NO and ET-1 appears to be complex and remains incompletely understood. One of the major actions of NO is the activation of soluble guanylate cyclase (sGC) with the subsequent generation of cGMP. Therefore, we undertook this study to test the hypothesis that NO regulates ET-1 production via the activation of the sGC/cGMP pathway. The results obtained indicated that the exposure of primary cultures of 4-wk-old ovine pulmonary arterial endothelial cells (4-wk PAECs) to the long-acting NO donor DETA NONOate induced both a dose- and time-dependent decrease in secreted ET-1. This decrease in ET-1 secretion occurred in the absence of changes in endothelin-converting enzyme-1 or sGC expression but in conjunction with a decrease in prepro-ET-1 mRNA. The changes in ET-1 release were inversely proportional to the cellular cGMP content. Furthermore, the NO-independent activator of sGC, YC-1, or treatment with a cGMP analog also produced significant decreases in ET-1 secretion. Conversely, pretreatment with the sGC inhibitor ODQ blocked the NO-induced decrease in ET-1. Therefore, we conclude that exposure of 4-wk PAECs to exogenous NO decreases secreted ET-1 resulting from the activation of sGC and increased cGMP generation.

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