Activation of Soluble Guanylate Cyclase and Potassium Channels Contribute to Relaxations to Nitric Oxide in Smooth Muscle Derived from Canine Femoral Veins

1999 ◽  
Vol 34 (3) ◽  
pp. 407-413 ◽  
Author(s):  
M. P. Bracamonte ◽  
J. C. Burnett ◽  
V. M. Miller
Hypertension ◽  
2015 ◽  
Vol 66 (suppl_1) ◽  
Author(s):  
Adam C Straub ◽  
Anh T Nguyen ◽  
Mizanur Rahaman ◽  
Stephanie M Mutchler ◽  
Megan Miller ◽  
...  

The inability nitric oxide (NO) to stimulate soluble guanylate cyclase (sGC) has been linked to numerous cardiovascular diseases (CVD) including hypertension. While several studies have defined the importance of sGC expression in the cardiovascular system, the basic mechanisms that regulate sGC activity remain incompletely understood. Here, we report for the first time that sGC heme iron redox state, which is essential for NO-induced sGC activation, is regulated by cytochrome B5 reductase 3 (CyB5R3). Genetic knockdown and pharmacological inhibition of CyB5R3 in primary rat vascular smooth muscle cells resulted in a 60% loss in cGMP production. Conversely, the sGC activator Bay 58-2667, which activates oxidized or heme free sGC, reversed these effects. Consistent with our cell culture work, purified protein studies demonstrate that CyB5R3 can directly reduce oxidized sGC heme iron and sensitize sGC to NO. To test the functional importance of Cyb5R3 activity, we cultured mouse thoracodorsal arteries with a pharmacological inhibitor of Cyb5R3 (ZINC 747) and performed vascular reactivity studies using pressure myography. Arteries treated with ZINC 747 showed decreased responsiveness the NO donor DETA-NONOate but increase sensitivity to Bay 58-2667. We then treated mice with 10mg/kg/day of ZINC 747 using osmotic mini pumps, which caused an increase in mean arterial blood pressure (107.5±3.4 vs 131±13.16) measured via radio telemetry. Lastly, translational studies reveal that the CyB5R3 T116S polymorphism with allele frequency 0.23 only in African Americans is unable to reduce sGC and correlates with increased blood pressure. Considering the defining role of sGC in NO signaling and the fact that the oxidation state of sGC may predict responses to NO therapies and new classes of sGC activator medications, we anticipate that these studies may significantly impact our understanding of biology, precision therapeutics (right drug for the right patient) and pharmacogenetics (T117S SNP based drug selection).


1997 ◽  
Vol 272 (3) ◽  
pp. L400-L406 ◽  
Author(s):  
K. D. Bloch ◽  
G. Filippov ◽  
L. S. Sanchez ◽  
M. Nakane ◽  
S. M. de la Monte

Nitric oxide (NO) has an important role in the pulmonary vasodilatation associated with the transition from fetal to neonatal life. NO activates pulmonary soluble guanylate cyclase (sGC), an obligate heterodimer composed of alpha1- and beta1-subunits, increasing synthesis of guanosine 3',5'-cyclic monophosphate (cGMP) and leading to vasodilation. In this study, regulation of sGC subunit expression during pulmonary development was examined. RNA blot hybridization revealed abundant alpha1- and beta1-subunit mRNA in lungs of late-gestation fetal and neonatal Sprague-Dawley rats, with markedly reduced levels detected in adult lungs. Pulmonary sGC enzyme activity in the presence of 1 mM sodium nitroprusside, a NO-donor compound, was approximately sevenfold greater in 1- and 8-day-old rats than in adult rats (P < 0.03). With the use of immunoblot techniques, pulmonary alpha1-subunit concentrations closely correlated with mRNA levels. With in situ hybridization, alpha1- and beta1-subunit mRNAs were readily detected in pulmonary vascular and bronchial smooth muscle cells as well as alveolar and serosal epithelial cells in lungs of 1-day-old rats. In adult lungs, sGC subunit mRNAs were present at low levels and were found nearly exclusively in bronchial and vascular smooth muscle cells. These results demonstrate that abundant pulmonary sGC is available to respond to the increased NO produced during the perinatal period. High-level expression of sGC subunit genes outside the vasculature of lungs of 1-day-old rats suggests an important role for NO-cGMP signal transduction in the perinatal regulation of pulmonary epithelial function and bronchial tone.


Reproduction ◽  
2021 ◽  
Vol 161 (1) ◽  
pp. 31-41
Author(s):  
Deepak S Hiremath ◽  
Fernanda B M Priviero ◽  
R Clinton Webb ◽  
CheMyong Ko ◽  
Prema Narayan

Timely activation of the luteinizing hormone receptor (LHCGR) is critical for fertility. Activating mutations in LHCGR cause familial male-limited precocious puberty (FMPP) due to premature synthesis of testosterone. A mouse model of FMPP (KiLHRD582G), expressing a constitutively activating mutation in LHCGR, was previously developed in our laboratory. KiLHRD582G mice became progressively infertile due to sexual dysfunction and exhibited smooth muscle loss and chondrocyte accumulation in the penis. In this study, we tested the hypothesis that KiLHRD582G mice had erectile dysfunction due to impaired smooth muscle function. Apomorphine-induced erection studies determined that KiLHRD582G mice had erectile dysfunction. Penile smooth muscle and endothelial function were assessed using penile cavernosal strips. Penile endothelial cell content was not changed in KiLHRD582G mice. The maximal relaxation response to acetylcholine and the nitric oxide donor, sodium nitroprusside, was significantly reduced in KiLHRD582G mice indicating an impairment in the nitric oxide (NO)-mediated signaling. Cyclic GMP (cGMP) levels were significantly reduced in KiLHRD582G mice in response to acetylcholine, sodium nitroprusside and the soluble guanylate cyclase stimulator, BAY 41-2272. Expression of NOS1, NOS3 and PKRG1 were unchanged. The Rho-kinase signaling pathway for smooth muscle contraction was not altered. Together, these data indicate that KiLHRD582G mice have erectile dysfunction due to impaired NO-mediated activation of soluble guanylate cyclase resulting in decreased levels of cGMP and penile smooth muscle relaxation. These studies in the KiLHRD582G mice demonstrate that activating mutations in the mouse LHCGR cause erectile dysfunction due to impairment of the NO-mediated signaling pathway in the penile smooth muscle.


2020 ◽  
Vol 318 (1) ◽  
pp. G23-G33
Author(s):  
Arjun Singh ◽  
Ipsita Mohanty ◽  
Jagmohan Singh ◽  
Satish Rattan

Presently, there are no studies examining the neuromodulatory effects of brain-derived neurotropic factor (BDNF) on the basal internal anal sphincter (IAS) tone and nonadrenergic noncholinergic (NANC) relaxation. To examine this, we determined the neuromuscular effects of BDNF on basal IAS smooth muscle tone and the smooth muscle cells (SMCs) and the effects of NANC nerve stimulation before and after high-affinity receptor tyrosine kinase receptor B (TrkB) antagonist K252a. We also investigated the mechanisms underlying BDNF-augmented increase in the IAS tone and NANC relaxation. We found that BDNF-increased IAS tone and SMC contractility were TTX resistant and attenuated by K252a. TrkB-specific agonist 7,8-dihydroxyflavone, similar to BDNF, also produced a concentration-dependent increase in the basal tone, whereas TrkB inhibitors K252a and ANA-12 produced a decrease in the tone. In addition, BDNF produced leftward shifts in the concentration-response curves with U46619 and ANG II (but not with bethanechol and K+ depolarization), and these shifts were reversed by K252a. Effects of Y27632 and Western blot data indicated that the BDNF-induced increase in IAS tone was mediated via RhoA/ROCK. BDNF-augmented NANC relaxation by electrical field stimulation was found to be mediated via the nitric oxide (NO)/soluble guanylate cyclase (sGC) pathway rather than via increased sensitivity to NO. In conclusion, the net effect of BDNF was that it caused an increase in the basal IAS tone via RhoA/ROCK signaling. BDNF also augmented NANC relaxation via NO/sGC. These findings may have relevance to the role of BDNF in the pathophysiology and therapeutic targeting of the IAS-associated rectoanal motility disorders. NEW & NOTEWORTHY These studies for the first time to our knowledge demonstrate that increased levels of brain-derived neurotrophic factor (BDNF; conceivably released from smooth muscle cells and/or the enteric neurons) has two major effects. First, BDNF augments the internal anal sphincter (IAS) tone via tyrosine kinase receptor B/thromboxane A2-receptor, angiotensin II receptor type 1/RhoA/ROCK signaling; and second, it increases nonadrenergic noncholinergic relaxation via nitric oxide/soluble guanylate cyclase. These studies may have relevance in therapeutic targeting in the anorectal motility disorders associated with the IAS.


2012 ◽  
Vol 688 (1-3) ◽  
pp. 49-55 ◽  
Author(s):  
Fábio H. da Silva ◽  
Mário A. Claudino ◽  
Fernando R. Báu ◽  
Julio A. Rojas-Moscoso ◽  
Fabíola Z. Mónica ◽  
...  

1999 ◽  
Vol 277 (4) ◽  
pp. L841-L847 ◽  
Author(s):  
Dechun Li ◽  
Nan Zhou ◽  
Roger A. Johns

The nitric oxide (NO)-cGMP signal transduction pathway plays an important role in the regulation of pulmonary vascular tone and resistance in pulmonary hypertension. A number of studies have demonstrated that endothelial (e) and inducible nitric oxide synthases (NOS) are upregulated in hypoxia-exposed rat lung. These changes in NOS expression have been found to correlate with the process of pulmonary vascular remodeling in hypoxia-induced pulmonary hypertension, and remodeling is increased in the absence of eNOS. In this study, we examined the expression and localization of soluble guanylate cyclase (sGC), the primary receptor for NO, in hypoxia- and normoxia-treated rat lungs. Male Sprague-Dawley rats were exposed to hypoxia (10% O2, normobaric) or normoxia for 1, 3, 5, and 21 days. The lungs were used for Western analysis of sGC protein, sGC enzyme activity, immunohistochemistry using antiserum against sGC α1- and β1-subunits, and nonradioactive in situ hybridization (NRISH) using a digoxigenin-labeled sGC α1-subunit cRNA probe. Western blot analysis revealed a more than twofold increase of sGC protein α1-subunit in rat lungs exposed to 3, 5, and 21 days of hypoxia, correlating well with sGC enzyme activity. Immunohistochemistry and NRISH demonstrated increased expression of sGC in the smooth muscle cells of the pulmonary arteries and arterioles in the hypoxic rat lungs when compared with normoxic controls. Based on our results, the upregulation of sGC may play an important role in the regulation of smooth muscle tone and pressure in the pulmonary circulation during chronic hypoxia.


1994 ◽  
Vol 179 (1) ◽  
pp. 71-80 ◽  
Author(s):  
D Beasley ◽  
M McGuiggin

Recent demonstration of cytokine-inducible production of nitric oxide (NO) in vascular smooth muscle cells (VSMC) from rat aorta has implicated VSMC-derived NO as a key mediator of hypotension in septic shock. Our studies to determine whether an inducible NO pathway exists in human VSMC have revealed a novel cytokine-inducible, NO-independent pathway of guanylate cyclase activation in VSMC from human saphenous vein (HSVSMC). Interleukin 1 (IL-1), tumor necrosis factor (TNF), interferon gamma (IFN-gamma) and Escherichia coli lipopolysaccharide (LPS) increased cGMP at 24 h, whereas IL-2 and IL-6 were ineffective. The effect of IL-1 on cyclic guanosine 3',5'-monophosphate (cGMP) was delayed, occurring after 6 h of exposure, and was maximal after 10 h. Methylene blue and LY83583 reversed the IL-1-induced increase in cGMP, suggesting that it was mediated by activation of soluble guanylate cyclase. However, IL-1-induced cGMP in HSVSMC was not inhibited by extracellular hemoglobin. Also, the effect of IL-1 on cGMP was not reversed by nitro- or methyl-substituted L-arginine analogs, aminoguanidine, or diphenyleneiodonium, all of which inhibit IL-1-induced NO synthase in rat aortic VSMC (RAVSMC). IL-1-induced cGMP in HSVSMC was also independent of tetrahydrobiopterin and extracellular L-arginine, as it was not affected by 2,4-diamino-6-hydroxyprytimidine, an inhibitor of tetrahydrobiopterin biosynthesis, and was similar in L-arginine-free and L-arginine-containing media. Analysis of NO synthase mRNA with the use of polymerase chain reaction indicates that levels of mRNA for inducible NO synthase are several orders of magnitude lower in IL-1-treated human HSVSMC than in IL-1-treated RAVSMC. IL-1-induced cGMP was also NO independent in human umbilical artery VSMC, and NO dependent in rat vena cava VSMC. Together these results indicate that IL-1 activates a novel NO-independent pathway of soluble guanylate cyclase activation in human VSMC.


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