Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.6.1.2 (guanylate cyclase)
 8,497 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Bradykinin and related kinins possess two different types of action (consisting of relaxation and contraction) in the isolated rat duodenum via their specific receptors. However, the mechanisms of these actions have not been fully elucidated. The present study was undertaken to investigate the effects of the agents affecting cyclic nucleotide metabolism on bradykinin-induced relaxations and on bradykinin- and des-Arg9-bradykinin-induced contractions. 2. Des-Arg9-bradykinin, B1 receptor agonist, and high concentrations of bradykinin elicited dose-dependent contractile responses in the rat duodenum, while low concentrations of bradykinin caused a dose-dependent relaxation in this tissue. 3. Nicotinic acid, an inhibitor of adenylate cyclase, inhibited the relaxation of rat duodenum induced by bradykinin at low concentrations in a non-competitive manner. However, the inhibitory efficacy of nicotinic acid against bradykinin was limited by 39.9% and this inhibition was not further increased by higher concentrations of nicotinic acid up to 10(-3) M. 4. Imidazole, an activator of cyclic nucleotide phosphodiesterase, caused a slight inhibition of the relaxant responses to low concentrations of bradykinin and of the contractile responses to des-Arg9-bradykinin and high concentrations of bradykinin in isolated rat duodenum. These inhibitions were also limited in efficacies and not increased by higher concentrations of imidazole. 5. Methylene blue, an agent that inhibits soluble guanylate cyclase, suppressed the contractions of rat duodenum induced by des-Arg9-bradykinin and high concentrations of bradykinin in a non-competitive manner. Again, these inhibitions were limited and further increase in the inhibitory efficacy was not observed in spite of increasing the methylene blue concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of the agents affecting cyclic nucleotide metabolism on the bradykinin- and des-Arg9-bradykinin-induced relaxations and contractions in isolated rat duodenum. 789 50

Soluble guanylate cyclase isolated from bovine and rat lung is a heterodimeric hemoprotein composed of alpha1 and beta1 subunits. The heme binding region has been localized to residues 1-385 of the beta1 subunit [beta1(1-385)], while the catalytic site(s) have been localized to the C-terminal region of sGC. There are four conserved histidine residues in the heme binding region of sGC. H220 and H346 are conserved among all known sGC subunits (alpha and beta), while H105 and H134 are conserved only in the beta subunits (beta1 and beta2). Site-directed mutagenesis was used to individually change each of the conserved histidines in sGC beta1(1-385) to alanine or glycine, and the resulting mutants were expressed in E. coli. All of the mutants except for H105A and H105G had heme bound as isolated. Imidazole (Im) was able to rescue heme binding to H105G when added to the growth medium and purification buffers. The heme in H105G isolated in the presence of imidazole [H105G(Im)] was ferric and a mixture of 5-coordinate, high-spin and 6-coordinate, low-spin complexes. After reduction, the ferrous heme in H105G(Im) was 5-coordinate, high-spin as indicated by resonance Raman spectroscopy. When imidazole in H105G(Im) was exchanged with N-methylimidazole (MeIm), the Fe-N(Im/MeIm) stretching frequency was shifted from 221 to 212 cm-1. A shift of this magnitude is expected when the ligand is directly coordinated to the heme iron. All of the data are consistent with the conclusion that H105 in the beta1 subunit is the heme proximal ligand.
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PMID:Identification of histidine 105 in the beta1 subunit of soluble guanylate cyclase as the heme proximal ligand. 952 70

When expressed in Escherichia coli, the heme domain [beta1(1-385)] of rat lung soluble guanylate cyclase (sGC) is isolated with a stoichiometric amount of bound heme [Zhao, Y., and Marletta, M. A. (1997) Biochemistry 36, 15959-15964]. Nitric oxide (NO) binding to the heme in beta1(1-385) leads to cleavage of the Fe-His bond and formation of a five-coordinate NO-heme complex. Addition of imidazole to the five-coordinate NO complex shifts the Soret peak from 399 to 420 nm, which appears to result from the formation of a six-coordinate NO complex. Removal of the added imidazole by gel filtration results in formation of the five-coordinate NO complex once again. The EPR spectrum of the putative six-coordinate NO complex has nine distinct derivative-shaped lines (a triplet of triplets), which is the signature spectrum of a six-coordinate NO complex with two nitrogen atoms as the axial ligands. [15N]Imidazole simplifies the six-coordinate NO complex EPR spectrum to six distinct derivative-shaped lines (a triplet of doublets), indicating that the other axial ligand in the six-coordinate NO complex is an imidazole molecule. These results show that NO binding to sGC not only leads to the cleavage of the Fe-His bond but also induces a conformational change which opens the heme proximal pocket large enough to accommodate an exogenous imidazole molecule. These observations have important implications for determining the NO activation mechanism of sGC.
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PMID:Structural changes in the heme proximal pocket induced by nitric oxide binding to soluble guanylate cyclase. 973 Aug 18

Intracellular signaling pathways involved in the survival of proliferating L1210 leukemia cells were investigated by using specific modulators. Among the various inhibitors tested, only 1H-[1,2,4]oxadiazole [4,3-a]quinoxalin-1-one (ODQ), a soluble guanylate cyclase (sGC) inhibitor, was found to induce a marked increase in caspase activity, which was associated with a loss of cell viability and a reduction in cGMP content. ODQ also provoked the processing of caspases-3 and -9, release of cytochrome c and, as early events, reduction of Bcl-2 content and dephosphorylation of Bad at Ser 112. Furthermore, YC-1, an sGC activator, and 8-Br-cGMP, a cell-permeant analogue of cGMP, exerted some protection against various apoptotic stimuli, such as serum deprivation or spermine accumulation. Although PD98059 (2'-amino-3'-methoxyflavone), an inhibitor of the p44/42 mitogen-activated protein kinase (MAPK) pathway, did not increase basal caspase activity, and ODQ did not affect p44/42 MAPK phosphorylation significantly, phorbol myristate acetate stimulated p44/42 MAPK and reduced caspase activation induced by ODQ, serum deprivation, and spermine in a p44/42-dependent manner. SB203580 (4-(4-fluorophenyl)-2-(4-methylsulfonylphenyl)-5-(4-pyridyl)1H-imidazole), a p38 MAPK inhibitor, also partially protected against ODQ-induced apoptosis by increasing p44/42 MAPK phosphorylation. In conclusion, these results suggest that sGC may be relevant both for survival of L1210 cells under basal growing conditions and for protection against various apoptotic stimuli. p44/42 MAPK activation may also confer some protection from apoptosis, but apparently through a pathway largely independent of cGMP.
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PMID:Control of survival of proliferating L1210 cells by soluble guanylate cyclase and p44/42 mitogen-activated protein kinase modulators. 1143 4

This study was designed to characterise the muscarinic receptor subtype responsible for acetylcholine-mediated in vitro pulmonary artery relaxation in rats and the importance of the presence of neostigmine (an anti-cholinesterase) during receptor characterisation. Cumulative administration of acetylcholine elicited concentration-dependent relaxation of phenylephrine (1 microM) precontracted preparations. Inclusion of neostigmine (10 microM) caused a parallel leftward shift with an increase of the pD(2) value (7.09 vs. 6.43) of the concentration-response curve of acetylcholine. The magnitude of maximum relaxation, however, was not affected. Using a range of conventional muscarinic receptor antagonists (atropine, pirenzepine, methoctramine, p-FHHSiD and tropicamide) and the highly selective Green Mamba muscarinic toxins (MT-3 and MT-7), it was found that muscarinic M(3) receptors are probably responsible for endothelium-dependent relaxation of the pulmonary artery upon acetylcholine challenge. Preincubation with N(G)-nitro-L-arginine methyl ester (L-NAME, 20 microM, a nitric oxide synthase inhibitor), but not N(G)-nitro-D-arginine methyl ester (D-NAME, 20 microM), abolished acetylcholine-elicited relaxation. Moreover, 6-anilino-5,8-quinolinedione (LY 83583, 1 microM) and methylene blue (1 microM) (both are guanylate cyclase inhibitors) markedly attenuated acetylcholine-elicited relaxation. However, the presence of indomethacin (3 microM, a cyclo-oxygenase inhibitor), (-)-perillic acid (30 microM, a p21(ras) blocker), 2-[2'-amino-3'-methoxy-phenyl]-oxana-phthalen-4-one (PD 98059) (10 microM, a p42/p44 mitogen-activated protein kinase inhibitor), 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB 203580) (1 microM, a p38 mitogen-activated protein kinase blocker), wortmannin (500 nM, a phosphatidylinositol-3 kinase inhibitor) and genistein (10 microM, a tyrosine kinase blocker) failed to alter acetylcholine-provoked pulmonary arterial relaxation. These results suggest that acetylcholine caused pulmonary arterial relaxation through the activation of muscarinic M(3) receptors in the endothelium. Moreover, the p21(ras)/mitogen-activated protein kinase pathway seems to play no role in mediating acetylcholine-elicited relaxation.
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PMID:Role of mitogen-activated protein kinase pathway in acetylcholine-mediated in vitro relaxation of rat pulmonary artery. 1175 66

Soluble guanylyl cyclase (sGC) is a cGMP-generating enzyme carrying a heme prosthetic group that functions as a nitric oxide (NO) sensor. sGC is present in most cells types, including the vascular endothelium, where its biological functions remain largely unexplored. Herein, we have investigated the role of sGC in angiogenesis and angiogenesis-related properties of endothelial cells (EC). Initially, we determined that sGC was present and enzymatically active in the chicken chorioallantoic membrane (CAM) during the days of maximal angiogenesis. In the CAM, inhibition of endogenous sGC inhibited neovascularization, whereas activation promoted neovessel formation. Using zebrafish as a model for vascular development, we did not detect any effect on vasculogenesis upon sGC blockade, but we did observe an abnormal angiogenic response involving the cranial and intersegmental vessels, as well as the posterior cardinal vein. In vitro, pharmacological activation of sGC or adenovirus-mediated sGC gene transfer promoted EC proliferation and migration, whereas sGC inhibition blocked tube-like network formation. In addition, sGC inhibition blocked the migratory response to vascular EC growth factor. Cells infected with sGC-expressing adenoviruses exhibited increased extracellular signal-regulated kinase 1/2 and p38 MAPK activation that was sensitive to sGC inhibition by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, suggesting that these mitogen-activated protein kinases are downstream effectors of sGC in EC. A functional role for p38 in cGMP-stimulated migration was demonstrated using SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole]; pharmacological inhibition of p38 attenuated BAY 41-2272 [5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-pyrimidin-4-ylamine] and sGC overexpression-induced EC mobilization. We conclude that sGC activation promotes the expression of angiogenesis-related properties by EC and that sGC might represent a novel target to modulate neovessel formation.
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PMID:Soluble guanylyl cyclase activation promotes angiogenesis. 1694 Apr 34

N,N'-Dialkyl-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamines show structural analogy with estrogens and selective estrogen receptor modulators. Because the vasodilator properties of these compounds are unknown, we investigated their potential to relax porcine coronary arteries and determined the mechanism(s) of relaxation. Isolated porcine coronary arterial rings were suspended in organ chambers, precontracted with KCl (30 mM), and the relaxant response was determined by measurement of changes in isometric force. Dependent on the chemical structure, the drugs induced concentration-dependent relaxation in rings with and without endothelium. N,N'-Dipropyl-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine (8) was most potent and showed a 12- to 15-fold higher vasodilatory effect than 17beta-estradiol (E2). The vasorelaxation was independent of endothelium. Calcium concentration-dependent contractions in high-potassium depolarizing medium were insurmountably inhibited by 8. The effect of the L-type Ca2+ channel activator (S)-(-)-Bay K 8644 [(S)-(-)-1,4-dihydro-2,6-dimethyl-5-nitro-4-[2-(trifluoromethyl)phenyl]-3-pyridine-carboxylic acid methyl ester], which induced a leftward shift of Ca2+ contraction, was blocked by 8. The relaxant response to 8 was unaffected by the estrogen receptor antagonist ICI 182,780 (7alpha-[9-[(4,4,5,5,5-pentafluoropentyl]-sulfinyl]nonyl]-estra-1,3,5(10)-triene-3,17beta-diol) and K+ channel blockers, i.e., TEA, glibenclamide, and 4-aminopyridine. Furthermore, the vasodilatory effect of 8 was unaffected by the adenylyl cyclase inhibitor SQ 22536 [9-(tetrahydro-2-furanyl)-9H-purin-6-amine], the guanylyl cyclase inhibitor ODQ [1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one], the protein kinase A inhibitor KT 5720 [(9S,10S,12R)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg: 3',2',1'-kl]pyrrolo[3,4-i][1,6]benzodiazocine-10-carboxylic acid hexyl ester], the protein kinase G inhibitor KT 5823 [(9S,10R,12R)-2,3,9,10,11,12-hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]benzodiazocine-10-carboxylic acid methyl ester], and the p38 mitogen-activated protein kinase (MAPK) inhibitor SB 203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-1H-imidazole]. Western blot analysis demonstrated that 8, unlike E2, raloxifene, and tamoxifen, failed to stimulate p38 MAPK. It is concluded that N,N'-dipropyl-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine induces endothelium-independent relaxation of coronary arteries; the mechanism apparently involves inhibition of L-type Ca2+ channels. The drug may be protective against cardiovascular diseases.
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PMID:Characterization of the relaxant response to N,N'-dipropyl-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine in porcine coronary arteries. 1732 23