Regulation of human neutrophil guanylate cyclase by metal ions, free radicals and the muscarinic cholinergic receptor

Serum Metabolomics and Ionomics Analysis of Hoof-Deformed Cows Based on LC-MS/MS and ICP-OES/MS

In order to explore the metabolic and ionic changes of hoof-deformed cows, the serum samples of 10 healthy cows (group C) and 10 hoof-deformed cows (group T) were analyzed by LC-MS/MS and ICP-OES/MS. The pathway enrichment of differential metabolites was analyzed by screening and identifying differential metabolites and ions and using a bioinformatics method. The integration of metabolomics and ionics was analyzed with ggplot2 software in R language, and verified by MRM target metabolomics. The results showed that 127 metabolites were screened by metabolomics, of which 81 were up-regulated (p < 0.05) and 46 were down-regulated (p < 0.05). The results of ICP-OES/MS showed that 13 kinds of ions such as K, Li, and Pb in serum of dairy cows were up-regulated, while 18 kinds of ions such as Al, Cu and Sb were down-regulated. The integrated analysis of metabolomics and ionics found that potassium ions were positively correlated with L-tyrosine, L-proline, thiamine and L-valine. Sodium ions were positively correlated with L-valine and negatively correlated with α-D-glucose. The results of high-throughput target metabolomics showed that the contents of L-proline, L-phenylalanine and L-tryptophan in serum of dairy cows increased significantly, which was consistent with the results of non-target metabolomics. In a word, the metabolism and ion changes in dairy cows with hoof deformation were revealed by metabolomics and ionics.

Soluble guanylyl cyclase activator YC-1 inhibits human neutrophil functions through a cGMP-independent but cAMP-dependent pathway

3-(5'-Hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1), a novel type of soluble guanylyl cyclase (sGC) activator, is useful in investigating the signaling of cGMP and may provide a new approach for treating cardiovascular diseases. Herein, YC-1 was demonstrated to inhibit the generation of superoxide anion (O2-) and the release of beta-glucuronidase release, to diminish the membrane-associated p47phox and to accelerate resequestration of cytosolic calcium in formyl-l-methionyl-l-leucyl-l-phenylalanine-activated human neutrophils. YC-1 not only directly promoted sGC activity and cGMP formation but also dramatically potentiated sodium nitroprusside-induced sGC activity and cGMP formation in human neutrophils. However, the synergistic increase in the amount of cGMP was inconsistent with its cellular response. Moreover, neither an sGC inhibitor nor protein kinase G inhibitors reversed the inhibitory effect of YC-1. Interestingly, YC-1 also increased the cAMP concentration and protein kinase (PK)A activity. The inhibitory effect of YC-1 was significantly enhanced by prostaglandin (PG)E1 and isoproterenol, and almost abolished by PKA inhibitors. These results show that cAMP, but not cGMP, mediates the YC-1-induced inhibition of human neutrophils. YC-1 increased the PGE1- and forskolin-induced but not 3-isobutyl-1-methylxanthine-produced cAMP formation, suggesting inhibition of phosphodiesterase. These findings thus reveal novel mechanism-mediated anti-inflammatory properties of YC-1 in human neutrophils, which can influence the progression of cardiovascular disease. cAMP, but not cGMP, plays an important role in the regulation of respiratory burst and degranulation in human neutrophils.

Inhibition of superoxide anion generation by YC-1 in rat neutrophils through cyclic GMP-dependent and -independent mechanisms

3-(5'-Hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1), a soluble guanylyl cyclase (sGC) activator, inhibited formyl-methionyl-leucyl-phenylalanine (fMLP)-induced superoxide anion (O(2)*(-)) generation and O(2) consumption in rat neutrophils (IC(50) values of 12.7+/-3.1 and 17.7+/-6.9 microM, respectively). Inhibition of O(2)*(-) generation by YC-1 was partially reversed by the cyclic GMP-lowering agent 6-anilinoquinoline-5,8-quinone (LY83583) and by the Rp isomer of 8-(4-chlorophenylthio)guanosine-3',5'-monophosphorothioate (Rp-8-pCPT-cGMPS), a cyclic GMP-dependent protein kinase inhibitor. In cell-free systems, YC-1 failed to alter O(2)*(-) generation during dihydroxyfumaric acid autoxidation, phorbol 12-myristate 13-acetate (PMA)-activated neutrophil particulate NADPH oxidase preparation, and arachidonic acid-induced NADPH oxidase activation. YC-1 increased cellular cyclic GMP levels through the activation of sGC and the inhibition of cyclic GMP-hydrolyzing phosphodiesterase activity. The plateau phase, but not the initial spike, of fMLP-induced [Ca(2+)](i) changes was inhibited by YC-1 (IC(50) about 15 microM). fMLP- but not PMA-induced phospholipase D activation was inhibited by YC-1 (IC(50) about 28 microM). Membrane-associated ADP-ribosylation factor and Rho A in cell activation was also reduced by YC-1 at a similar concentration range. Neither cytosolic protein kinase C (PKC) activity nor PKC membrane translocation was altered by YC-1. YC-1 did not affect either fMLP-induced phosphatidylinositol 3-kinase activation or p38 mitogen-activated protein kinase phosphorylation, but slightly attenuated the phosphorylation of extracellular signal-regulated kinase. Collectively, these results indicate that the inhibition of the fMLP-induced respiratory burst by YC-1 is mediated by cyclic GMP-dependent and -independent signaling mechanisms.

Inhibition of extracellular Ca(2+) entry by YC-1, an activator of soluble guanylyl cyclase, through a cyclic GMP-independent pathway in rat neutrophils

The effects of a soluble guanylyl cyclase (sGC) activator, 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1), on formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated [Ca(2+)](i) elevation in rat neutrophils were examined. YC-1 produced a concentration-dependent inhibition of [Ca(2+)](i) elevation. Pretreatment of neutrophils with YC-1 did not enhance its inhibitory effect. YC-1 also inhibited the [Ca(2+)](i) changes caused by ionomycin. In a biphasic model, measuring the [Ca(2+)](i) stimulation by fMLP in a Ca(2+)-free medium followed by reintroduction of Ca(2+), YC-1 mainly affected Ca(2+) influx. YC-1 also inhibited active and passive Mn(2+) influx, and this inhibitory effect was not attenuated by the sGC inhibitor 6-anilino-5,8-quinolinequinone (LY83583). Sodium nitroprusside did not affect the fMLP-stimulated [Ca(2+)](i) changes. Pretreatment of neutrophils with the cyclic GMP-dependent protein kinase inhibitor 8-(4-chlorophenylthio) guanosine-3',5'-monophosphorothioate, Rp-isomer (Rp-8-pCPT-cGMPS), LY83583, the protein phosphatase 2B inhibitor cyclosporin A, or the protein kinase inhibitor staurosporine did not attenuate the inhibition of [Ca(2+)](i) by YC-1. YC-1 inhibited the fMLP-stimulated protein tyrosine phosphorylation. These results indicate that cyclic GMP does not play an important role in the regulation of [Ca(2+)](i) in rat neutrophils. Inhibition of fMLP-stimulated [Ca(2+)](i) changes by YC-1 is mainly via the blockade of Ca(2+) entry through the inhibition of tyrosine kinase activity, but not the stimulation of protein kinase C and protein phosphatase 2B.

Induction of human neutrophil apoptosis by nitric oxide donors: evidence for a caspase-dependent, cyclic-GMP-independent, mechanism

This study investigated the regulatory effects of the major inflammatory mediator, nitric oxide (NO), on human neutrophil apoptosis in vitro. Co-culture of human neutrophils with the NO donors GEA 3162 (1,2,3,4-oxatriazolium,5-amino-3-(3,4-dichlorophenyl)-chloride) (10-100 microM) and 3-morpholino-sydnonimine (SIN-1) (0.3-3 mM) caused a dramatic and concentration-dependent induction of apoptosis. However, N-formyl-methionyl-leucyl-phenylalanine (FMLP)-induced neutrophil activation (actin reorganization and chemotaxis) was inhibited by GEA 3162 treatment. The pro-apoptotic effects of the NO donors were (i) unaffected by the soluble guanylate cyclase inhibitor LY-83583 (6-anilino-5,8-quinolinedione; 100 microM), (ii) antagonized by superoxide dismutase (6 microg/mL), (iii) mimicked by exogenous peroxynitrite (at concentrations >100 microM), and (iv) inhibited by the caspase inhibitor Z-Val-Ala-DL-Asp-fluoromethylketone (100 microM). The pro-apoptotic effect of the NO donors was not mimicked by the cell-permeable cyclic nucleotide analogue, N6,2-O-dibutyrylguanosine-3',5'-cyclic monophosphate (dibutyryl-cGMP) at concentrations < or =0.2 mM. Indeed, at high concentrations (> or =2 mM), dibutyryl-cGMP caused an inhibition of apoptosis. These results suggest that NO-mediated apoptosis, although caspase-dependent, is mediated by a cGMP-independent mechanism and involves the concurrent generation of oxygen free radicals and, potentially, peroxynitrite. Our data reveal a unique role for NO in inflammatory responses with differential effects upon neutrophil activation and survival, with important implications for the successful resolution of inflammation.

Effects of 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and Nomega(6)-nitro-L-arginine methyl ester (NAME) on cyclic GMP levels during muscarinic activation of tracheal smooth muscle

The effects of carbachol on the cyclic GMP (cGMP) content of bovine tracheal smooth muscle in the absence of phosphodiesterase inhibitors were evaluated. Carbachol (1 x 10(-5) M) induced two cGMP peaks, at 20 and 60 sec. Both cGMP signals were carbachol concentration-dependent (1 x 10(-11) to 1 x 10(-5) M), the first being higher than the second. The cGMP signal induction was studied using an inhibitor of the soluble guanylyl cyclase (GC), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), and a nitric oxide (NO) synthase inhibitor, Nomega(6)-nitro-L-arginine methyl ester (NAME). ODQ (1 x 10(-7) M) did not affect the second cGMP peak but abolished the first peak, suggesting that a soluble GC may be involved. NAME (1 x 10(-4) M) did not affect the cGMP signals, but changed their 2:1 ratio and also induced a time-shift of the first peak to 10 sec and the second to 50 sec. These results indicate that the NO-soluble GC cascade is not responsible for these muscarinic effects on cGMP levels.

Effect of different ozone concentrations on the neurogenic contraction and relaxation of guinea pig airways

Prejunctional and postjunctional effects of several ozone (O3) concentrations, including those found in highly polluted cities, were evaluated in guinea pig airways. Animals bred in O3-free conditions were exposed to air or O3 (0.3, 0.6 or 1.2 ppm) during 4 h, and studied 16-18 h later. Tracheal and bronchial rings were studied in organ baths. Electrical field stimulation (EFS) (100 V, 2 ms, 10 s) was given at increasing frequencies (0.25-16 Hz). Some tissues received atropine (2 microM) and/or propranolol (10 microM). Concentration-response curves to carbachol, isoproterenol, nitroprusside, and substance P were constructed. In tracheas, almost all O3 concentrations decreased the relaxation at low EFS frequencies, but had no effect on the propranolol-resistant (i-NANC) relaxation, suggesting that only adrenergic relaxation was affected. This was a prejunctional effect, since O3 did not modify the responses to isoproterenol. Relaxation induced by a nitric oxide (NO) donor, nitroprusside, was not affected by O3, which agrees with the lack of O3-effect on i-NANC system. O3 did not modify the EFS-induced e-NANC contraction in atropine-treated bronchi, nor the contraction caused by exogenous substance P. By contrast, in bronchi without atropine, 1.2 ppm O3 increased the e-NANC contraction induced by the highest EFS (16 Hz). O3 increased the maximum responses to carbachol in tracheas (1.2 ppm) and bronchi (0.6 and 1.2 ppm). In conclusion, we found that: a) O3 decreased adrenergic relaxation in guinea pig tracheas at low EFS frequencies through a prejunctional alteration; b) O3 did not modify the i-NANC relaxation in tracheas, at least the NO-mediated; c) O3 added a cholinergic component to the bronchial slow-phase (e-NANC) contraction evoked by EFS; and d) O3 enhanced the cholinergic responses in trachea and bronchi by a postjunctional mechanism.

Nitric oxide inhibits neutrophil beta 2 integrin function by inhibiting membrane-associated cyclic GMP synthesis

The aim of this investigation was to identify the mechanism by which nitric oxide inhibits neutrophil beta 2 integrin dependent adherence. Isolated rat neutrophils from blood and peritoneal exudates were exposed for 2 min to nitric oxide generated by diethylamine-NO at rates between 1.6 and 138 nmol/min. Exposure to nitric oxide at rates less than 14 nmol/min had no effect on adherence. Exposure to 14 to 56 nmol nitric oxide/min inhibited beta 2 integrin dependent adherence to endothelial cells, nylon columns, and fibrinogen-coated plates, but higher concentrations had no significant effect on adherence. Adherence by beta 2 integrins could be restored by incubating cells with dithioerythritol, phorbol 12-myristate 13-acetate, or 8-bromo cyclic GMP. Elevations in cellular cyclic GMP concentration were associated with adherence, but this did not occur after cells were exposed to concentrations of nitric oxide that inhibited beta 2 integrin-dependent adherence. Elevations in cyclic GMP did occur after cells were incubated with dithioerythritol or phorbol 12-myristate 13-acetate. Concentrations of nitric oxide that inhibited beta 2 integrin-dependent adherence also inhibited catalytic activity of membrane associated guanylate cyclase and binding of atrial natriuretic peptide, but were insufficient to activate cytosolic guanylate cyclase. Nitric oxide did not inhibit neutrophil oxidative burst or degranulation, nor effect beta 2 integrin expression or adherence that did not depend on beta 2 integrins, nor cause oxidative stress identified in terms of cellular glutathione concentration or protein nitrotyrosine. The results indicate that nitric oxide inhibited beta 2 integrins in a concentration-dependent fashion by inhibiting cell-surface transduction of signals linked to the activity of membrane-bound guanylate cyclase. The inhibitory effect could be overcome by providing cells with cyclic GMP exogenously or by stimulating cytosolic guanylate cyclase.

Inhibition of human neutrophil beta2-integrin-dependent adherence by hyperbaric O2

Animal and clinical investigations have reported that exposure to hyperbaric O(2) improved the outcome of some reperfusion injuries. Animal studies have suggested that this may be due to an inhibition of leukocyte adherence to injured endothelium. This investigation tested the hypothesis that exposure to hyperbaric O(2) would inhibit beta2-integrin-dependent adherence of human neutrophils. Subjects were exposed to O(2) at partial pressures of up to 3 atmospheres absolute (ATA; 1 ATA = 0.1 MPa) for 45 min, and neutrophil binding to nylon columns and to fibrinogen-coated surfaces was measured. Exposure to O(2) at 2.8 or 3.0 ATA inhibited beta2-integrin-dependent neutrophil adherence but had no effect on the cell-surface expression of beta2-integrins, respiratory burst in response to phorbol ester, or non-beta2-integrin-dependent adherence to plastic plates coated with a fibronectin-like protein. beta2-Integrin adherence was restored by incubating blood with 8-bromoguanosine 3',5'-cyclic monophosphate (cGMP) and hyperbaric O(2) inhibited synthesis of cGMP by neutrophils stimulated with N-formyl-Met-Leu-Phe (FMLP). In studies of cell fractions, the activity of membrane guanylate cyclase was found to be increased by incubation with FMLP as well as by atrial natriuretic peptide (ANP) plus ATP. Hyperbaric O(2) had no effect on the basal activity of soluble or membrane-bound guanylate cyclase. However, hyperbaric O(2) inhibited the function of both the extracellular binding domain of membrane guanylate cyclase as well as intracellular catalytic activity. There are approximately 7,300 membrane guanylate cyclase molecules per cell, based on binding studies with ANP, with a dissociation constant of approximately 450 pM. Hyperbaric O(2) inhibits the function of human neutrophil beta2-integrins by a process linked to impaired synthesis of cGMP.

The role of cyclic nucleotides in neutrophil migration

1. The literature concerning the effects of cAMP and especially cGMP on neutrophil migration is reviewed. 2. Experiments with agents that enhance cGMP level, and with electroporated neutrophils in which cGMP was introduced, show that the nucleotide has different effects. There is a maximal stimulation at a specific concentration while higher concentrations are less effective or even inhibitory. 3. Some physiologically active peptides such as granulocyte-macrophage colony-stimulating factor (GM-CSF), atrial natriuretic factor, and endothelin appear to modify neutrophil migration via a cGMP-dependent mechanism. 4. Dependent on concentration and conditions (random migration vs. fMLP-activated migration, using nitric oxide (NO), NO donors, and inhibitors of NO synthase), NO has stimulatory or inhibitory effects on neutrophil migration. 5. The differential effects of cGMP and cAMP on neutrophil migration are discussed with regard to intracellular actions, metabolism, interaction with calcium, and relation to structural changes required for cell movement.

Molsidomine inhibits the chemoattractant-induced respiratory burst in human neutrophils via a no-independent mechanism

3-Morpholino-sydnonimine (SIN-1) is a NO-releasing compound which mimics the effects of cGMP through activation of soluble guanylyl cyclase. Its prodrug, molsidomine (SIN-10), does not release NO but does modulate various cell functions. These findings prompted us to study the effects of SIN-10 and SIN-1 on the respiratory burst in human neutrophils. SIN-10 was more effective than SIN-1 in inhibiting superoxide anion (O2-) formation induced by N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMet-Leu-Phe) and by C5a. The effects of SIN-1 and SIN-10 on O2- formation were additive or less than additive, indicating the sydnonimines acted through a common mechanism. The sydnonimines showed no effect on O2- formations induced by gamma-hexachlorocyclohexane, arachidonic acid and a phorbol ester. They did not inhibit O2- formation induced by xanthine oxidase, by autoxidation of pyrogallol and in a cell-free system from HL-60 leukemic cells. Neutrophils did not convert SIN-10 to SIN-1 as assessed by O2 consumption which accompanies NO release from SIN-1. The cell-permeant analogue of cGMP, N2,2'-O-dibutyryl guanosine 3':5'-monophosphate (Bt2cGMP), and SIN-10 but not SIN-1 inhibited fMet-Leu-Phe-induced O2 consumption. SIN-1 and SIN-10 slightly enhanced agonist binding to formyl peptide receptors, whereas Bt2cGMP was inhibitory. The sydnonimines did not affect GTP hydrolysis of heterotrimeric regulatory guanine nucleotide-binding proteins in HL-60 membranes. SIN-1 but not SIN-10 stimulated ADP-ribosylation of a 39-kDa protein in the cytosol of HL-60 cells. SIN-10 reduced fMet-Leu-Phe-induced rises in cytosolic Ca2+ concentration in neutrophils. These data suggest that SIN-10 inhibits the respiratory burst via a NO-independent mechanism which may involve inhibition of rises in cytosolic Ca2+ concentration.

Differential inhibition and potentiation of chemoattractant-induced superoxide formation in human neutrophils by the cell-permeant analogue of cyclic GMP, N2,2'-O-dibutyryl guanosine 3':5'-cyclic monophosphate

Human neutrophils possess a superoxide (O2-)-forming NADPH oxidase which is activated by the chemoattractants, N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMet-Leu-Phe), complement C5a, platelet-activating factor and leukotriene B4. We studied the roles of cAMP and cGMP in the regulation of O2- formation using the cell-permeant analogues of cyclic nucleotides, N6,2'-O-dibutyryl adenosine 3':5'-cyclic monophosphate (Bt2cAMP) and N2,2'-O-dibutyryl guanosine 3':5'-cyclic monophosphate (Bt2cGMP). Bt2cAMP inhibited O2- formation induced by these chemoattractants to similar extents. Bt2cGMP as low as 10 mumol/l significantly inhibited O2- formation induced by fMet-Leu-Phe at a submaximally effective concentration (50 nmol/l), and Bt2cGMP was more effective in diminishing O2- formation than Bt2cAMP. In contrast, Bt2cGMP did not affect O2- formation induced by fMet-Leu-Phe at a maximally effective concentration (1 mumol/l). Bt2cGMP (0.1 and 1 mmol/l) enhanced O2- formation induced by 0.1 mumol/1 C5a by 23% and 49%, respectively, and Bt2cGMP antagonized inhibition of O2- formation caused by Bt2cAMP. Bt2cGMP inhibited platelet-activating factor-induced O2- formation to a lesser extent than Bt2cAMP and had no effect on that induced by leukotriene B4. Bt2cAMP and Bt2cGMP had no effect on O2- formation induced by NAF, gamma-hexachlorocyclohexane, phorbol myristate acetate, A 23187 and arachidonic acid. Our data suggest that: 1. Bt2cAMP generally inhibits chemoattractant-stimulated O2- formation. 2. Bt2cGMP inhibits fMet-Leu-Phe- and platelet-activating factor-stimulated O2- formation but potentiates C5a-induced O2- formation.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of cGMP in the extinction of the reactions of identified neurons of the edible snail in response to acetylcholine

The possible role of cGMP in the regulation of the extinction of the reactions of the RPa4, RPa3, and LPa3 neurons of the edible snail in response to acetylcholine (ACh), applied rhythmically to the soma of the neuron by means of microiontophoresis, has been investigated. It was demonstrated that activators of guanylate cyclase which increased the level of cGMP in the cell, namely, sodium nitroprusside and sodium azide (5.10(-4)-10(-3) mole/liter), when applied intracellularly, intensify the extinction of inward transmembrane current and of depolarization of the membrane in response to ACh. The hypothesis of the participation of cGMP-dependent phosphorylation of membrane proteins in the regulation of the rate of development, depth, and duration of short-lived plasticity of the cholinoreceptors of the neuron is proposed.