Mechanisms of relaxant activity of the nitric oxide-independent soluble guanylyl cyclase stimulator BAY 41-2272 in rat tracheal smooth muscle

2010 ◽  
Vol 645 (1-3) ◽  
pp. 158-164 ◽  
Author(s):  
Haroldo A. Toque ◽  
Fabíola Z.T. Mónica ◽  
Rafael P. Morganti ◽  
Gilberto De Nucci ◽  
Edson Antunes
1995 ◽  
Vol 269 (2) ◽  
pp. F212-F217 ◽  
Author(s):  
K. S. Lau ◽  
O. Nakashima ◽  
G. R. Aalund ◽  
L. Hogarth ◽  
K. Ujiie ◽  
...  

Cytokines increase the expression of the inducible (type II) nitric oxide synthase (NOS) in macrophages, liver, and renal epithelial cells. Previously, we found that cultured rat medullary interstitial cells (RMIC) contain high levels of soluble guanylyl cyclase. To determine whether these cells can also produce NO, we studied the effects of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) on NO production, NOS II mRNA, and NOS II protein expression. Both TNF-alpha and IFN-gamma, in the presence of a low concentration of the other cytokine, caused dose-dependent increases in NO production. Exposure to TNF-alpha and IFN-gamma stimulated the production of NOS II mRNA, as determined by Northern blotting. Restriction mapping of reverse transcription-polymerase chain reaction products indicated that normal cells contained macrophage NOS II, whereas cytokine-stimulated cells contained primarily vascular smooth muscle NOS II and some macrophage NOS II. The appearance of NOS II protein was demonstrated by Western blotting. RMIC cell guanosine 3',5'-cyclic monophosphate accumulation increased 129-fold in response to the cytokines. NOS inhibitors decreased nitrite production. We conclude that 1) TNF-alpha and IFN-gamma induce the expression of vascular smooth muscle NOS II and production of NO in RMIC, and 2) NO acts as an autocrine activator of the soluble guanylyl cyclase in RMIC.


2010 ◽  
Vol 637 (1-3) ◽  
pp. 171-177 ◽  
Author(s):  
Fernando R. Báu ◽  
Fabiola Z.T. Mónica ◽  
Fernanda B.M. Priviero ◽  
Lineu Baldissera ◽  
Gilberto de Nucci ◽  
...  

1993 ◽  
Vol 71 (12) ◽  
pp. 938-945 ◽  
Author(s):  
Zhenguo Liu ◽  
Kanji Nakatsu ◽  
James F. Brien ◽  
E. Danielle Beaton ◽  
Gerald S. Marks ◽  
...  

Sequestration of nitric oxide (NO) by subcellular fractions isolated from bovine pulmonary arterial medial layer (BPA) and rabbit platelets (RP) was studied utilizing a novel chemiluminescence – headspace gas technique. Sequestration in all fractions was similarly rapid (5 min) and remained constant for at least 30 min. When incubated with 108 pmol of NO, the BPA mitochondrial, microsomal, and nuclear fractions sequestered 22.8 ± 1.9, 20.5 ± 2.2 and 15.2 ± 3.6% of the NO, respectively (n = 14). However, significantly more of the 108 pmol of NO, 36.8 ± 2.8 and 32.9 ± 3.6%, respectively, was sequestered by the BPA homogenate (about 2 mg protein/mL) and BPA cytosolic fraction (about 1 mg protein/mL) (n = 19). Also, RP cytosolic fraction (about 3 mg protein/mL) sequestered a greater amount of NO than any BPA fraction when incubated with 108 pmol of NO (83.0 ± 1.0%; n = 3). Analysis of the binding data obtained for the BPA homogenate and cytosolic fraction was consistent with the existence of two binding sites, one site with a Kd of approximately 100 nM and another with a Kd of approximately 1 μM. Both the BPA homogenate fraction and the cytosolic fraction as well as the RP cytosolic fraction were shown to have soluble guanylyl cyclase activity. The nitrovasodilator sodium nitroprusside (SNP) caused a concentration-dependent increase in the activity of this enzyme in all these fractions. Maximum stimulations caused by 1 mM SNP in BPA homogenate fraction, BPA cytosolic fraction, and RP cytosolic fraction were equivalent to 2-, 4- and 3-fold increases in catalytic activity, respectively. No effect of SNP was observed in BPA mitochondrial, microsomal, or nuclear fraction. Prior incubation of BPA and RP cytosolic fractions with authentic NO significantly stimulated the soluble guanyiyl cyclase activity. In both the BPA and RP cytosolic fractions, maximal stimulation brought about by prior incubation with authentic NO was equivalent to approximately 60% of that caused by 100 μM SNP. Thus, incubation of subcellular fractions from two nitrovasodilator-sensitive tissues with authentic NO resulted in significant sequestration of the free radical in these fractions and a concentration-dependent activation of the soluble guanylyl cyclase. In conclusion, the chemiluminescence – headspace gas technique is a suitable method for the study of NO sequestration in subcellular fractions of various tissues. Also, this study demonstrates that NO is sequestered preferentially by subcellular fractions of BPA and RP that contain soluble guanylyl cyclase activity, and that the sequestration of NO in these fractions stimulates the catalytic activity of this enzyme.Key words: nitric oxide, vascular smooth muscle, platelets, soluble guanylyl cyclase.


Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Samba Couloubaly ◽  
Nazish Sayed ◽  
Jamila Hedhli ◽  
Padmamalini Baskaran ◽  
Annie Beuve

The enzyme soluble guanylyl cyclase (sGC) increases cellular level of the second messenger cGMP upon stimulation by nitric oxide (NO), whose role is exemplified in the cardiovascular system where it governs smooth muscle cell proliferation, vascular relaxation and platelet aggregation. Various pathologies like diabetes, hypertension and hypercholesterolemia are associated with enhanced oxidative stress with increased formation of reactive oxygen (ROS) and nitrogen species (RNS). We recently showed that cysteines beta1C243 and beta1C122 are S-nitrosylated in sGC leading to its desensitization. We have now identified by Mass Spectrometry, two additional cysteines (beta1C571 and alpha1C516) as potentially modified. Our hypothesis is that loss in vascular reactivity in oxidative pathologies is mediated, in part, by desensitization of sGC via thiols oxidation. We studied the effect of oxidative stress on sGC in primary vascular smooth muscle cells (VSMC) by directly exposing them to hydrogen peroxide (H2O2) in the absence or presence of a catalase inhibitor Amino-Triazole (AT). H2O2 induced inhibition of NO-stimulated sGC activity in VSMC and in COS 7 cells transiently transfected with sGC. Desensitization of sGC was further increased in VSMC treated with both H2O2 and AT. Next, we conducted mutational analysis of the 4 cysteines to assess their involvement in redox sensing. Replacement of C571 and C122 eliminated the oxidative-dependent desensitization observed in the wild-type. In addition, peroxynitrite, a strong oxidant, inhibited the NO-stimulated sGC activity in a purified system without oxidation of the heme. In conclusion, our results suggest that sGC activity is directly modulated by the redox state of the cells. Moreover, the identified 4 cysteines can be modified by both ROS and RNS suggesting a complex modulation. Ultimately, our goal is to determine whether loss of vascular reactivity in oxidative pathophysiologies is in part mediated by desensitization of sGC and what are the involved cysteines. This work was supported by NIH GM067640, HL089771.


1998 ◽  
Vol 275 (4) ◽  
pp. H1148-H1157 ◽  
Author(s):  
Chin-Chen Wu ◽  
Shiu-Jen Chen ◽  
Mao-Hsiung Yen

We investigated whether a complete inhibition of nitric oxide (NO) formation caused by bacterial endotoxin (lipopolysaccharide, LPS) in vivo prevents the hypotension and restores the vascular hyporeactivity to normal in vivo and ex vivo. The combination of dexamethasone (Dex; 3 mg/kg at 30 min before LPS) plus aminoguanidine (AG; 15 mg/kg at 2 h after LPS) inhibited the overproduction of nitrate (an indicator of NO) in the plasma and aortic smooth muscle and also prevented the development of the delayed hypotension in rats treated with LPS for 6 h. However, the vascular hyporeactivity to norepinephrine (NE) was only partially improved either in vivo or ex vivo in endotoxemic rats treated with Dex plus AG. Pretreatment of aortic rings with N ω-nitro-l-arginine methyl ester (l-NAME) or 1 H-[1,2,4]oxidazolo[4,3-a]quinoxalin-1-one (ODQ) enhanced the contraction to NE in rings obtained from LPS-treated rats, but not in those from Dex plus AG-treated endotoxemic rats. Methylene blue, an inhibitor of soluble guanylyl cyclase (GC), completely restored contractions to NE and aortic cGMP levels to normal either in LPS-treated rats or in Dex plus AG-treated endotoxemic rats, whereas the cGMP level was partially inhibited by ODQ in LPS-treated rats only. These results suggest that non-NO mediator(s) also activates soluble GC during endotoxemia. Interestingly, we found that in the presence of tetraethylammonium (an inhibitor of K+ channels) plusl-NAME or charybdotoxin [a specific inhibitor of large-conductance Ca2+-activated K+(KCa) channels] plus ODQ, the vascular hyporeactivity to NE in the LPS-treated group was also completely restored to normal. In addition, in the presence ofl-NAME or ODQ, the vascular hyporeactivity to high K+ was abolished in rings from the LPS-treated group. These results suggest that LPS causes the production of other mediator(s), in addition to NO, which also stimulates soluble GC (i.e., increases the formation of cGMP) and then activates the large-conductance KCa channels in the vascular smooth muscle causing vascular hyporeactivity.


2018 ◽  
Vol 156 ◽  
pp. 168-176 ◽  
Author(s):  
Alexander Kollau ◽  
Bernd Gesslbauer ◽  
Michael Russwurm ◽  
Doris Koesling ◽  
Antonius C.F. Gorren ◽  
...  

Author(s):  
Saeideh Saadat ◽  
Farzaneh Naghdi ◽  
Vahideh Ghorani ◽  
Hassan Rakhshandeh ◽  
Mohammad Hossein Boskabady

In this study we aimed to examine the relaxant effect of berberine, a compound extracted from a variety of herbs, on rat tracheal smooth muscle (TSM) and its possible mechanism(s). Cumulative concentrations of berberine (20, 65, 200 and 600 μg/mL) were added on pre-contracted TSM by methacholine or KCl in non-incubated or incubated tissues with atropine, chlorpheniramine, propranolol, diltiazem, glibenclamide, indomethacin, L-NG-nitro arginine methyl ester (L-NAME) and papaverine. The relaxant effects of theophylline (0.2, 0.4, 0.6 and 0.8 mM) as positive control and saline (1 mL) as negative control were also examined in non-incubated tissues. Berberine showed significant and concentration-dependent relaxant effects in non-incubated tissues contracted by KCl and methacholine (p<0.01 to p<0.001). There was no significant difference in the relaxant effects of berberine between non-incubated and incubated tissues with atropine, propranolol, diltiazem, glibenclamide, and papaverine. The relaxant effects of second concentrations of berberine in incubated tissues with L-NAME, its three lower concentration in incubated tissues with chlorpheniramine and its all concentrations in incubated tissues with indomethacin were significantly lower than non-incubated tissues (p<0.05 to p<0.001). The EC50 values of berberine in incubated tissues with chlorpheniramine was significantly higher than the non-incubated condition (p<0.05). Our findings reveal a relatively potent relaxant effect of berberine that is lower than the effect of theophylline. Proposed mechanisms for the relaxant effect of berberine are histamine (H1) receptor blockade, inhibition of cyclooxygenase pathways and/or nitric oxide formation.  


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