The interactive effects of fluoride and N-formyl-L-methionyl-L-leucyl-L-phenylalanine on superoxide production and cAMP levels in human neutrophils

1983 ◽  
Vol 61 (7) ◽  
pp. 569-578 ◽  
Author(s):  
Kenneth Wong
Keyword(s):  
Adenylate Cyclase ◽  
Interactive Effects ◽  
Human Neutrophils ◽  
Intracellular Camp ◽  
Chemotactic Peptide ◽  
Lag Period ◽  
Camp Levels ◽  
Kinetics Of ◽  
Generating System

The kinetics of superoxide (O2−) production and intracellular cAMP levels were monitored in human neutrophils incubated in vitro with sodium fluoride and the chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP). F− activation of both the O2−-generating system, NAD(P)H oxidase, and adenylate cyclase was characterized by a prolonged lag period of 8 to 10 min at 37 °C. Adenylate cyclase agonists or cAMP analogues which inhibited FMLP-induced O2− bursts did not affect O2− production of F−-activated cells. Prior treatment of cells with F− suppressed the short rapid burst elicited by FMLP but not the binding of the tripeptide. FMLP reciprocally decreased the lag period of the F−-induced burst by 40 to 50% and, in the case of cells incubated at temperatures below 37 °C, increased the rate of O2− production. A similar potentiating effect of FMLP on F−-induced elevation of intracellular cAMP levels was observed.

Modulation of human neutrophil function in vitro by gastrin

1997 ◽  
Vol 153 (3) ◽  
pp. 475-483 ◽  
Author(s):  
M De la Fuente ◽  
M Carrasco ◽  
A Hernanz
Keyword(s):  
Superoxide Anion ◽  
Latex Bead ◽  
Human Neutrophils ◽  
Intracellular Camp ◽  
Maximal Effect ◽  
Superoxide Anion Production ◽  
Phagocytic Process ◽  
Anion Production ◽  
Camp Levels

Abstract We have studied the effects in vitro of gastrin-17 and gastrin-34, at concentrations from 10−14 m to 10−6 m, on several of the functions of peripheral blood human neutrophils, i.e. adherence to substrate, mobility (spontaneous and directed by a chemical gradient or chemotaxis), ingestion of inert particles (latex beads) and cells (Candida albicans) and superoxide anion production. Both gastrins inhibited several steps of the phagocytic process of human neutrophils, such as mobility and ingestion. By contrast, these peptides increased adherence and had no effect on superoxide anion production. In general, these effects were significant at peptide concentrations between 10−12 m and 10−8 m with a maximal effect at 10−10 m. In addition, gastrin peptides induced a significant increase in intracellular cAMP levels at 30, 60 and 120 s. Moreover, the inhibitory effect of gastrin-17 on the ingestion capacity of neutrophils (latex bead phagocytosis) was similar to that obtained with EGTA, a well-known extracellular calcium chelating compound. Gastrin-17 was found to inhibit completely the stimulation of latex bead phagocytosis in neutrophils caused by the calcium ionophore A23187. These results suggest that gastrin is a negative modulator of the phagocytic process of human neutrophils, and that this effect might involve an increase in intracellular cAMP levels and a decrease in calcium entry into the cells. Journal of Endocrinology (1997) 153, 475–483

scholarly journals Exposure ofN-Formyl-l-Methionyl-l-Leucyl-l-Phenylalanine-Activated Human Neutrophils to the Pseudomonas aeruginosa-Derived Pigment 1-Hydroxyphenazine Is Associated with Impaired Calcium Efflux and Potentiation of Primary Granule Enzyme Release

1999 ◽  
Vol 67 (10) ◽  
pp. 5157-5162 ◽  
Author(s):  
Grace Ramafi ◽  
Ronald Anderson ◽  
Annette Theron ◽  
Charles Feldman ◽  
Graham W. Taylor ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Human Neutrophils ◽  
Intracellular Camp ◽  
Enzyme Release ◽  
Calcium Efflux ◽  
Spectrofluorimetric Method ◽  
Activated Neutrophils ◽  
Camp Levels ◽  
Primary Granule

ABSTRACT The effects of pathologically relevant concentrations (0.38 to 12.5 μM) of the proinflammatory, Pseudomonas aeruginosa-derived pigment 1-hydroxyphenazine (1-hp) on Ca2+ metabolism and intracellular cyclic AMP (cAMP) inN-formyl-l-methionyl-l-leucyl-l-phenylalanine (FMLP; 1 μM)-activated human neutrophils, as well as on the release of myeloperoxidase (MPO) and elastase from these cells, have been investigated in vitro. Ca2+ fluxes were measured by the combination of a fura-2/AM-based spectrofluorimetric method and radiometric procedures, which together enable distinction between net efflux and influx of the cation, while radioimmunoassay and colorimetric methods were used to measure cAMP and granule enzymes, respectively. Coincubation of neutrophils with 1-hp did not affect intracellular cAMP levels or the FMLP-activated release of Ca2+ from intracellular stores but did retard the subsequent decline in the chemoattractant-induced increase in the concentration of cytosolic free Ca2+. These effects of 1-hp on the clearance of Ca2+ from the cytosol of activated neutrophils were associated with decreased efflux of the cation from the cells and increased release of MPO and elastase, while the delayed store-operated influx of the cation into the cells was unaffected by the pigment. The plasma membrane Ca2+-ATPase rather than a Na+-Ca2+ exchanger appeared to be the primary target of 1-hp. These observations suggest that the proinflammatory interactions of 1-hp with activated human neutrophils are a consequence of interference with the efflux of cytosolic Ca2+ from these cells.

Ticlopidine and Clopidogrel (SR 25990C) Selectively Neutralize ADP Inhibition of PGE1-Activated Platelet Adenylate Cyclase in Rats and Rabbits

1991 ◽  
Vol 65 (02) ◽  
pp. 186-190 ◽  
Author(s):  
G Defreyn ◽  
C Gachet ◽  
P Savi ◽  
F Driot ◽  
J P Cazenave ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Adenylate Cyclase ◽  
Direct Effect ◽  
Cyclic Nucleotide ◽  
Camp Accumulation ◽  
Rabbit Platelets ◽  
Camp Levels ◽  
Kinetics Of ◽  
Camp Elevation ◽  
Rat Platelets

SummaryTiclopidine and its potent analogue, clopidogrel, are powerful inhibitors of ADP-induced platelet aggregation. In order to improve the understanding of this ADP-selectivity, we studied the effect of these compounds on PGE1-stimulated adenylate cyclase and on the inhibition of this enzyme by ADP, epinephrine and thrombin. Neither drug changed the basal cAMP levels nor the kinetics of cAMP accumulation upon PGEj-stimulation in rat or rabbit platelets, which excludes any direct effect on adenylate cyclase or on cyclic nucleotide phosphodiesterase. However, the drop in cAMP levels observed after addition of ADP to PGEr stimulated control platelets was inhibited in platelets from treated animals. In contrast, the drop in cAMP levels produced by epinephrine was not prevented by either drug in rabbit platelets. In rat platelets, thrombin inhibited the PGEX-induced cAMP elevation but this effect seems to be entirely mediated by the released ADP. Under these conditions, it was not surprising to find that clopidogrel also potently inhibited that effect of thrombin on platelet adenylate cyclase. In conclusion, ticlopidine and clopidogrel selectively neutralize the ADP inhibition of PGEr activated platelet adenylate cyclase in rats and rabbits.

scholarly journals PGE2-mediated inhibition of T cell p59fynis independent of cAMP

1999 ◽  
Vol 277 (2) ◽  
pp. C302-C309 ◽  
Author(s):  
Mashkoor A. Choudhry ◽  
Zulfiqar Ahmed ◽  
Mohammed M. Sayeed
Keyword(s):  
T Cells ◽  
T Cell ◽  
Adenylate Cyclase ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Prostaglandin E ◽  
Intracellular Camp ◽  
Sprague Dawley ◽  
Cell Functions ◽  
Camp Levels

We recently observed that prostaglandin E2(PGE2)-mediated suppression of T cell functions could result from an attenuation of p59fynprotein tyrosine kinase activity. The present study evaluated the effects of an adenylate cyclase agonist (forskolin) and antagonist (SQ-22536), as well as those of cAMP analogues (dibutyryl cAMP and 8-bromo- cAMP), on T cell p59fynkinase activity. The study allowed us to assess whether PGE2-mediated activation of adenylate cyclase by itself or the elevation in intracellular cAMP levels is an integral event in the modulation of anti-CD3-linked p59fynactivation in T cells. The experiments were carried out with splenic T cells from male Sprague-Dawley rats. A 30–50% suppression in the autophosphorylation and the kinase activity of p59fynin T cells incubated with PGE2or forskolin was observed. Pretreatment of T cells with SQ-22536 prevented significant PGE2-mediated inhibition of T cell p59fynkinase activity. In contrast, no change in p59fynautophosphorylation and kinase activity in T cells treated with cAMP analogues was observed. These data suggest that PGE2-mediated suppression of p59fynautophosphorylation and kinase activity in T cells is dependent on the activation of adenylate cyclase and independent of the elevation in cAMP levels.

Chloroquine stimulates absorption and inhibits secretion of ileal water and electrolytes

1982 ◽  
Vol 243 (2) ◽  
pp. G117-G126
Author(s):  
R. Fogel ◽  
G. W. Sharp ◽  
M. Donowitz
Keyword(s):  
Cholera Toxin ◽  
Calcium Content ◽  
Intracellular Camp ◽  
Rabbit Ileum ◽  
Camp Content ◽  
Serosal Surface ◽  
Ileal Absorption ◽  
Camp Levels

The effects of chloroquine diphosphate, a drug with "'membrane-stabilizing" properties, were studied on basal ileal absorption and on ileal secretion induced by increased intracellular cAMP levels and calcium (serotonin). The studies were performed on rat (in vivo) and rabbit ileum (in vitro). Intraluminal chloroquine (10(-4) M) reversed cholera toxin- and theophylline-induced secretion in rat ileum but did not alter the cholera toxin- and theophylline-induced increases in cAMP content. Addition of chloroquine (10(-4) M) to the mucosal surface of rabbit ileum did not alter basal active electrolyte transport or the serotonin-induced decreased Na and Cl absorption but inhibited the theophylline-induced C1 secretion. Addition of chloroquine (10(-4)) M) to the serosal surface stimulated net Na and Cl absorption. This effect may involve intracellular calcium. Chloroquine increased the rabbit ileal calcium content and decreased 45Ca2+ influx from the serosal surface. Both the mucosal and serosal effects of chloroquine described led to a net increase in absorptive function of the intestine and should prove useful in developing treatment of diarrheal diseases.

scholarly journals Changes in gene expression in the Ras/adenylate cyclase system of Saccharomyces cerevisiae: correlation with cAMP levels and growth arrest.

1993 ◽  
Vol 4 (7) ◽  
pp. 757-765 ◽  
Author(s):  
M Russell ◽  
J Bradshaw-Rouse ◽  
D Markwardt ◽  
W Heideman
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Adenylate Cyclase ◽  
Oxidative Metabolism ◽  
Growth Arrest ◽  
Intracellular Camp ◽  
Adenylate Cyclase System ◽  
Diauxic Shift ◽  
Yeast Saccharomyces Cerevisiae ◽  
Camp Levels

Levels of cyclic 3',5'-cyclic monophosphate (cAMP) play an important role in the decision to enter the mitotic cycle in the yeast, Saccharomyces cerevisiae. In addition to growth arrest at stationary phase, S. cerevisiae transiently arrest growth as they shift from fermentative to oxidative metabolism (the diauxic shift). Experiments examining the role of cAMP in growth arrest at the diauxic shift show the following: 1) yeast lower cAMP levels as they exhaust their glucose supply and shift to oxidative metabolism of ethanol, 2) a reduction in cAMP is essential for traversing the diauxic shift, 3) the decrease in adenylate cyclase activity is associated with a decrease in the expression of CYR1 and CDC25, two positive regulators of cAMP levels and an increase in the expression of IRA1 and IRA2, two negative regulators of intracellular cAMP, 4) mutants carrying disruptions in IRA1 and IRA2 were unable to arrest cell division at the diauxic shift and were unable to progress into the oxidative phase of growth. These results indicate that changes cAMP levels are important in regulation of growth arrest at the diauxic shift and that changes in gene expression plays a role in the regulation of the Ras/adenylate cyclase system.

scholarly journals A pharmacologically distinct cyclic AMP receptor is responsible for the regulation of gp80 expression in Dictyostelium discoideum.

1990 ◽  
Vol 10 (7) ◽  
pp. 3297-3306 ◽  
Author(s):  
P C Ma ◽  
C H Siu
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Dictyostelium Discoideum ◽  
Surface Glycoprotein ◽  
Intracellular Camp ◽  
Cell Surface Glycoprotein ◽  
Cyclase Activation ◽  
Adenylate Cyclase Activation ◽  
Camp Receptor

The EDTA-resistant cell-cell adhesion expressed at the aggregation stage of Dictyostelium discoideum is mediated by a cell surface glycoprotein of Mr 80,000 (gp80). The expression of gp80 is developmentally regulated by cyclic AMP (cAMP). In vitro nuclear run-on experiments show that transcription of the gp80 gene is initiated soon after the onset of development. The basal level of gp80 transcription is significantly augmented by exogenous cAMP pulses. Interestingly, in analog studies, 2'-deoxy-cAMP, 8-bromo-cAMP, and N6-monobutyryl-cAMP are all capable of inducing a rapid accumulation of gp80 mRNA, suggesting the presence of a unique cAMP receptor that responds equally well to these analogs. To determine whether intracellular cAMP plays a role in the regulation of gp80 expression, caffeine was used to block cAMP-induced receptor-mediated adenylate cyclase activation. Expression of gp80 mRNA was blocked in caffeine-treated cells but could be substantially restored by treatment with exogenous cAMP pulses, suggesting that adenylate cyclase activation is not required. gp80 expression was also examined in the signal transduction mutants synag 7 and frigid A. In both mutants, gp80 was expressed at the basal level. Pulses of cAMP as well as 2'-deoxy-cAMP and N6-monobutyryl-cAMP were capable of restoring the normal level of gp80 expression in synag 7 cells. These results, taken together, indicate bimodal regulation of gp80 expression during development and the involvement of a novel cAMP receptor in the transmembrane signalling pathway that regulates gp80 gene expression.

Ammonia promotes accumulation of intracellular cAMP in differentiating amoebae of Dictyostelium discoideum

Development ◽  
1990 ◽  
Vol 109 (3) ◽  
pp. 715-722
Author(s):  
B.B. Riley ◽  
S.L. Barclay
Keyword(s):  
Dictyostelium Discoideum ◽  
Active Species ◽  
Spore Formation ◽  
Intracellular Camp ◽  
Simultaneous Exposure ◽  
High Ph ◽  
Camp Hydrolysis ◽  
Extracellular Camp ◽  
Camp Levels

We used sporogenous mutants of Dictyostelium discoideum to investigate the mechanism(s) by which exogenous NH4Cl and high ambient pH promote spore formation during in vitro differentiation. The level of NH4Cl required to optimize spore formation is correlated inversely with pH, indicating that NH3 rather than NH4+ is the active species. The spore-promoting activity of high ambient pH (without exogenous NH4Cl) was eliminated by the addition of an NH3-scavenging cocktail, suggesting that high pH promotes spore differentiation by increasing the ratio of NH3:NH4+ secreted into the medium by developing cells. High ammonia levels and high pH stimulated precocious accumulation of intracellular cAMP in both sporogenous and wild-type cells. In both treatments, peak cAMP levels equaled or exceeded control levels and were maintained for longer periods than in control cells. In contrast, ammonia strongly inhibited accumulation of extracellular cAMP without increasing the rate of extracellular cAMP hydrolysis, indicating that ammonia promotes accumulation of intracellular cAMP by inhibiting cAMP secretion. These results are consistent with previous observations that factors that raise intracellular cAMP levels increase spore formation. Lowering intracellular cAMP levels with caffeine or progesterone inhibited spore formation, but simultaneous exposure to these drugs and optimal concentrations of NH4Cl restored both cAMP accumulation and spore formation to normal levels. These data suggest that ammonia, which is a natural Dictyostelium morphogen, favors spore formation by promoting accumulation or maintenance of high intracellular cAMP levels.

LH release is facilitated by agents that alter cyclic AMP-generating system

1984 ◽  
Vol 246 (1) ◽  
pp. E44-E51 ◽  
Author(s):  
M. J. Cronin ◽  
W. S. Evans ◽  
E. L. Hewlett ◽  
M. O. Thorner
Keyword(s):  
Adenylate Cyclase ◽  
Cholera Toxin ◽  
Regulatory Protein ◽  
Dependent Manner ◽  
Calcium Dependent ◽  
Camp Analogue ◽  
Lh Release ◽  
Integral Proteins ◽  
Generating System

The issue of whether the adenosine 3',5'-monophosphate (cAMP)-generating system contributes to luteinizing hormone (LH) release was addressed by using several complementary probes in vitro. Pertussis toxin is considered to modify covalently an inhibitory adenylate cyclase regulatory protein. Treatment of gonadotrophs with this toxin increased both basal LH release and the efficacy of gonadotropin-releasing hormone (GnRH)-stimulated LH release with no apparent effect on GnRH potency. Cholera toxin, which probably activates adenylate cyclase by covalently altering another regulatory protein, forskolin, which directly stimulates the catalytic subunit of adenylate cyclase, and the cAMP analogue 8-Br-cAMP amplified both basal LH release (in a dose-dependent manner) and GnRH-stimulated LH release after a lag of 1 (cholera toxin and 8-Br-cAmP) and 4 (forskolin) h. It is noteworthy that these belated effects occurred in spite of the fact that cellular cAMP accumulation was markedly increased within 30 min after cholera toxin and at 1 min after forskolin addition. There was no change in total radioimmunoassayable LH (cellular + released) in either the basal or GnRH-treated cells after cholera toxin and forskolin for up to 24 h. Finally, the forskolin-amplified LH release was reversible and calcium dependent because D-600, EDTA, and calcium-free medium inhibited this effect. These results, generated with three complementary probes that affect integral proteins of the adenylate cyclase complex, suggest a function for cAMP in modulating LH release.

Aminophylline and progesterone prevent inflammation-induced preterm parturition in the mouse†

2019 ◽  
Vol 101 (4) ◽  
pp. 813-822 ◽  
Author(s):  
Bronwen R Herbert ◽  
Danijela Markovic ◽  
Ektoras Georgiou ◽  
Pei F Lai ◽  
Natasha Singh ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Phosphodiesterase Inhibitor ◽  
Adenosine Monophosphate ◽  
Cytokine Gene Expression ◽  
Intracellular Camp ◽  
Myometrial Cells ◽  
Anti Inflammatory ◽  
Camp Levels

Abstract Although progesterone (P4) supplementation is the most widely used therapy for the prevention of preterm labor (PTL), reports of its clinical efficacy have been conflicting. We have previously shown that the anti-inflammatory effects of P4 can be enhanced by increasing intracellular cyclic adenosine monophosphate (cAMP) levels in primary human myometrial cells. Here, we have examined whether adding aminophylline (Am), a non-specific phosphodiesterase inhibitor that increases intracellular cAMP levels, to P4 might improve its efficacy using in vivo and in vitro models of PTL. In a mouse model of lipopolysaccharide (LPS)-induced PTL, we found that the combination of P4 and Am delayed the onset of LPS-induced PTL, while the same dose of P4 and Am alone had no effect. Pup survival was not improved by either agent alone or in combination. Myometrial prolabor and inflammatory cytokine gene expression was reduced, but the reduction was similar in P4 and P4/Am treated mice. There was no effect of the combination of P4 and Am on an ex vivo assessment of myometrial contractility. In human myometrial cells and myometrial tissue explants, we found that the combination had marked anti-inflammatory effects, reducing cytokine and COX-2 mRNA and protein levels to a greater extent than either agent alone. These data suggest that the combination of P4 and Am has a more potent anti-inflammatory effect than either agent alone and may be an effective combination in women at high-risk of PTL.

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