STUDIES ON THE EFFECT OF CILOSTAZOL ON THE PROSTAGLANDINS PRODUCTION DURING ADP-INDUCED PLATELET AGGREGATION WITH ENDOTHELIAL CELLS

1987 ◽  
Author(s):  
T Chijiwa ◽  
T Shiragiku ◽  
S Kato ◽  
T Igawa ◽  
Y Kimura
Keyword(s):  
Endothelial Cells ◽  
Platelet Aggregation ◽  
Clinical Effect ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Inhibitory Effect ◽  
Camp Level ◽  
Camp Production ◽  
Potent Inhibitory Effect ◽  
Stimulation Of

It has been clinically reported that cilostazol has a potent inhibitory effect on platelet aggregation without changing the prostacyclin level. This study was undertaken to elucidate this clinical effect by a technique developed by us in which platelet aggregation could be evaluated in the presence of cultured endothelial cells. Human umbililical cord vein endothelial cells (HUVEC) were coated (cultured for a few days supplemented with 10% fetal claf serum) on the inner surface of glass cuvette, and platelet aggregation was traced by the stimulation of citrated-PRP with 7.5 μM ADP in this cuvette. The 6-keto-prostaglandin F1α (6-k-PGF) and thromboxane B2 (TXB) produced in the supernatant of the stimulated PRP were measured by radioimmunoassay (Amersham). The cyclic adenosine monophosphate (cAMP) level in platelets and HUVEC was measured by radioimmunoassay (YAMASA). Cilostazol showed a potent inhibitory effect on platelet aggregation in the presence of HUVEC by the suppresion of TXB production, but not by the suppression of 6-k-PGF production. Cilostazol stimulated cAMP production in both platelets and HUVEC. On the other hand, aspirin also showed an inhibitory effect on platelet aggregation in the presence of HUVEC, but suppressed production of both TXB and 6-k-PGF.As a result, the clinical effect of cilostazol was confirmed by the fact that TXA2 production in a platelet/HUVEC coexisting system was specifically suppressed.

Differential Effect of Halothane and Forskolin on Platelet Cytosolic Ca (2+) Mobilization and Aggregation 

1998 ◽  
Vol 89 (2) ◽  
pp. 401-410 ◽  
Author(s):  
Francois Corbin ◽  
Gilbert Blaise ◽  
Remy Sauve
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activating Factor ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Inhibitory Effect ◽  
Signaling Cascade ◽  
Aggregation Process ◽  
Camp Production ◽  
Biochemical Pathways ◽  
Stimulation Of

Background Previous works have suggested that the impairment of platelet aggregation by halothane was partly related to a stimulation of cyclic adenosine monophosphate (cAMP) production, to an inhibitory effect on Ca2+ signaling, or both. Intracellular Ca2+ measurements therefore were undertaken, first to determine the critical steps in the platelet CaZ+ signaling cascade most likely to be affected by halothane or by an increase in cAMP production, and second to establish if the effect of halothane involves aggregation-related biochemical pathways triggered by an increase in internal Ca2+. Methods Human washed platelets were treated with halothane or forskolin for 5 min before application of either platelet-activating factor, thrombin, U46619, or thapsigargin. The cytosolic Ca2+ concentration ([Ca2+]i) was measured with the fluorescent Ca2+ indicator fura-2. Nephelometric measurements were also performed to assay the aggregation process. Results Our results indicate that pretreating platelets with halothane leads to a partial impairment of the [Ca2+]i increase induced either by U46619, thrombin, or platelet-activating factor, but this had no significant effect on the [Ca2+]i response triggered by thapsigargin. In addition, our results show that halothane inhibits platelet aggregation triggered by U46619, but not by thapsigargin. Conversely, forskolin completely inhibited the [Ca2+]i response to U46619 and thapsigargin and prevented platelet aggregation induced by both agonists. Conclusions These results suggest that halothane and cAMP exert their effects on platelet aggregation and Ca2+ signaling through different mechanisms, and that halothane cannot impair platelet aggregation independently of phospholipase C stimulation.

Protein kinase C activation and positive and negative agonist regulation of 3′, 5′-cyclic adenosine monophosphate levels in cultured rat Sertoli cells

1993 ◽  
Vol 128 (6) ◽  
pp. 568-572 ◽  
Author(s):  
Lars Eikvar ◽  
Kristin Austlid Taskén ◽  
Winnie Eskild ◽  
Vidar Hansson
Keyword(s):  
Sertoli Cells ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Dependent Manner ◽  
Camp Production ◽  
Camp Phosphodiesterase ◽  
Concentration Dependent Manner ◽  
Camp Formation ◽  
Pkc Activation ◽  
Stimulation Of

The present study examines the effects of 12-0-tetradecanoylphorbol-13-acetate (TPA) on agonist-regulated 3′, 5′-cyclic adenosine monophosphate (cAMP) formation and cAMP-mediated effects in cultured Sertoli cells from immature rats. Concentration-dependent stimulation of cAMP levels by follicle-stimulating hormone (FSH) was inhibited dramatically by the coaddition of 100 nmol/l TPA, which exerted a similar inhibition of glucagon- and isoproterenol-stimulated cAMP production. These results show that protein kinase C (PKC) activation by TPA attenuates Gs-protein-mediated agonist activation of cAMP production. (− )-N6(R)-Phenylisopropyladenosine (L-PIA), an A1-adenosine receptor agonist, inhibited cAMP stimulation by FSH in a concentration-dependent manner. When LPIA was added in increasing concentrations simultaneously with 100 nmol/l TPA, the L-PIA still inhibited FSH-stimulated cAMP production in a concentration-dependent manner. In the presence of TPA, the half-inhibitory concentration (IC50) for L-PIA inhibition of cAMP formation was reduced by more than one order of magnitude, indicating that PKC activation by TPA increases the sensitivity of Sertoli cells to G-protein-mediated agonist inhibition of cAMP production. The inhibitory effects of TPA on FSH-stimulated cAMP production were still observed when cAMP phosphodiesterase activity was inhibited by 1 mmol/l methylisobutylxanthine or when the activity of Gxi-protein was eliminated by pretreatment with 100 μg/l pertussis toxin. Taken together, the results indicate that PKC activation inhibits agonist-dependent stimulation of cAMP production by phosphorylation of components common to all the activating agonists used, and not via stimulation of Gi-protein activity or degradation of cAMP by cAMP phosphodiesterase activity. The increased sensitivity to L-PIA inhibition of cAMP formation induced by TPA may simply be a result of the reduced activity of the agonist-receptor/Gs-protein/C complex.

Effect of dopamine on adenylate cyclase activity, polyphosphoinositide metabolism and cytosolic calcium concentrations in frog pituitary melanotrophs

1993 ◽  
Vol 136 (3) ◽  
pp. 421-429 ◽  
Author(s):  
L. Desrues ◽  
M. Lamacz ◽  
B. G. Jenks ◽  
H. Vaudry ◽  
M. C. Tonon
Keyword(s):  
Calcium Channels ◽  
Inositol Trisphosphate ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Cytosolic Calcium ◽  
Inhibitory Effect ◽  
Intermediate Lobe ◽  
Camp Production ◽  
Membrane Phospholipids ◽  
Voltage Dependent

ABSTRACT It has previously been shown that dopamine plays a pivotal role in the regulation of α-melanocyte-stimulating hormone (α-MSH) secretion from the intermediate lobe of the pituitary. In the present study, we have investigated the various intracellular mechanisms that are associated with the action of dopamine on frog pituitary melanotrophs. Dopamine reduced forskolin-stimulated cyclic adenosine monophosphate (cAMP) production and the inhibitory effect of dopamine was blocked by the dopaminergic D2 receptor antagonist sulpiride. The D2 receptor agonist apomorphine inhibited incorporation of [3H]inositol into membrane phospholipids. Dopamine also inhibited the formation of inositol trisphosphate and provoked accumulation of phosphatidylinositol bisphosphate. The inhibitory effect of dopamine on inositol trisphosphate production was mimicked by D2 receptor agonists and blocked by sulpiride. Using a double-wavelength microfluorimetric approach, we found that dopamine caused a rapid and transient decrease in K+-evoked stimulation of intracellular calcium concentration. The timecourses of the responses of the various intracellular messengers indicate that blockage of voltagedependent calcium channels is the primary event associated with activation of dopamine D2 receptors, while inhibition of polyphosphoinositide breakdown, related to blockage of voltage-dependent calcium channels, and reduction of cAMP production are secondary events which may contribute to the sustained inhibitory effect of dopamine on α-MSH release. Journal of Endocrinology (1993) 136, 421–429

Thrombospondin-1 induces platelet activation through CD36-dependent inhibition of the cAMP/protein kinase A signaling cascade

Blood ◽  
2010 ◽  
Vol 116 (20) ◽  
pp. 4297-4306 ◽  
Author(s):  
Wayne Roberts ◽  
Simbarashe Magwenzi ◽  
Ahmed Aburima ◽  
Khalid M. Naseem
Keyword(s):  
Platelet Aggregation ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Inhibitory Effect ◽  
Src Kinases ◽  
Thrombospondin 1 ◽  
Dependent Inhibition ◽  
Kinase A

Abstract Cyclic adenosine monophosphate (cAMP)-dependent signaling modulates platelet function at sites of vascular injury. Here we show that thrombospondin-1 (TSP-1) prevents cAMP/protein kinase A (PKA) signaling through a CD36-dependent mechanism. Prostaglandin E1 (PGE1) induced a robust inhibition of both platelet aggregation and platelet arrest under physiologic conditions of flow. Exogenous TSP-1 reduced significantly PGE1-mediated inhibition of both platelet aggregation and platelet arrest. TSP-1 prevented PGE1-stimulated cAMP accrual and phosphorylation of PKA substrates, through a mechanism requiring phosphodiesterase3A. TSP-1 also inhibited VASP phosphorylation stimulated by the nonhydrolyzable cAMP analog, 8-bromo-cAMP, indicating that it may regulate cAMP-mediated activation of PKA. The inhibitory effect of TSP-1 on cAMP signaling could be reproduced with a peptide possessing a CD36 binding sequence of TSP-1, while the effects of TSP-1 were prevented by a CD36 blocking antibody. TSP-1 and the CD36 binding peptide induced phosphorylation of Src kinases, p38 and JNK. Moreover, inhibition of Src kinases blocked TSP-1–mediated regulation of cAMP concentrations and the phosphorylation of VASP, indicating that TSP-1 modulated the cAMP/PKA signaling events through a tyrosine kinase-dependent pathway downstream of CD36. These data reveal a new role for TSP-1 in promoting platelet aggregation through modulation of the cAMP-PKA signaling pathway.

Dobutamine Antagonizes Epinephrine's Biochemical and Cardiotonic Effects 

1998 ◽  
Vol 89 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Richard C. Prielipp ◽  
Drew A. MacGregor ◽  
Roger L. Royster ◽  
Neal D. Kon ◽  
Michael H. Hines ◽  
...  
Keyword(s):  
Artery Bypass ◽  
Phase 1 ◽  
Human Lymphocytes ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Camp Production ◽  
Isobolographic Analysis ◽  
Camp Generation ◽  
Vitro Model

Background Patients may receive more than one positive inotropic drug to improve myocardial function and cardiac output, with the assumption that the effects of two drugs are additive. The authors hypothesized that combinations of dobutamine and epinephrine would produce additive biochemical and hemodynamic effects. Methods The study was performed in two parts. Phase 1 used human lymphocytes in an in vitro model of cyclic adenosine monophosphate (cAMP) generation in response to dobutamine (10(-8) to 10(-4) M) or epinephrine (10(-9) M to 10(-5) M), and dobutamine and epinephrine together. Phase 2 was a clinical study in patients after aortocoronary artery bypass in which isobolographic analysis compared the cardiotonic effects of dobutamine (1.25, 2.5, or 5 microg x kg(-1) x min(-1)) or epinephrine (10, 20, or 40 ng x kg(-l) x min(-1)), alone or in combination. Results In phase 1, dobutamine increased cAMP production 41%, whereas epinephrine increased cAMP concentration approximately 200%. However, when epinephrine (10(-6) M) and dobutamine were combined, dobutamine reduced cAMP production at concentrations between 10(-6) to 10(-4) M (P = 0.001). In patients, 1.25 to 5 microg x kg(-1) x min(-1) dobutamine increased the cardiac index (CI) 15-28%. Epinephrine also increased the CI with each increase in dose. However, combining epinephrine with the two larger doses of dobutamine (2.5 and 5microg x kg(-1) x mi(-1)) did not increase the CI beyond that achieved with epinephrine and the lowest dose of dobutamine (1.25 microg x kg(-1) x min(-1)). In addition, the isobolographic analysis for equieffective concentrations of dobutamine and epinephrine suggests subadditive effects. Conclusions Dobutamine inhibits epinephrine-induced production of cAMP in human lymphocytes and appears to be subadditive by clinical and isobolographic analyses of the cardiotonic effects. These findings suggest that combinations of dobutamine and epinephrine may be less than additive.

scholarly journals Increased intracellular cyclic adenosine monophosphate inhibits T lymphocyte-mediated cytolysis by two distinct mechanisms.

1988 ◽  
Vol 167 (6) ◽  
pp. 1963-1968 ◽  
Author(s):  
L S Gray ◽  
J Gnarra ◽  
E L Hewlett ◽  
V H Engelhard
Keyword(s):  
Cholera Toxin ◽  
T Lymphocyte ◽  
Pertussis Toxin ◽  
Target Cell ◽  
Cyclic Adenosine Monophosphate ◽  
Second Messenger ◽  
Adenosine Monophosphate ◽  
Dose Dependent Fashion ◽  
Dose Dependent ◽  
Stimulation Of

Cholera toxin (CT), but not pertussis toxin (PT), treatment of cloned murine CTL inhibited target cell lysis in a dose-dependent fashion. The effects of CT were mimicked by forskolin and cyclic adenosine monophosphate (cAMP) analogues. Inhibition of cytotoxicity by CT and cAMP analogs was mediated in part by attenuation of conjugate formation. Additionally, both CT and cAMP analogs blocked the increase in intracellular Ca2+ induced by stimulation of the TCR complex by mAbs. These findings indicate that cAMP inhibits the activity of CTL by two distinct mechanisms and suggests a role for this second messenger in CTL-mediated cytolysis.

MATURATIONAL CHANGES IN SHEEP OVARIAN FOLLICLES: GONADOTROPHIC STIMULATION OF CYCLIC AMP PRODUCTION BY ISOLATED THECA AND GRANULOSA CELLS

1978 ◽  
Vol 89 (1) ◽  
pp. 166-172 ◽  
Author(s):  
T. J. Weiss ◽  
D. T. Armstrong ◽  
J. E. A. McIntosh ◽  
R. F. Seamark
Keyword(s):  
Cyclic Amp ◽  
Granulosa Cells ◽  
Follicle Stimulating Hormone ◽  
Adenosine Monophosphate ◽  
Ovarian Follicles ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Camp Production ◽  
Stimulation Of ◽  
Stimulating Hormone

ABSTRACT Theca and granulosa tissues isolated from sheep ovarian follicles of different sizes were incubated in the presence of human chorionic gonadotrophin (HCG; 5 IU/ml) or follicle stimulating hormone (FSH; 5 μg NIH-FSH-S11/ml) for 40 min. Changes in the total amounts of cyclic 3′,5′-adenosine monophosphate (cAMP) were used as an index of the responsiveness of these preparations to the hormones. Thecal tissue of both large (4–6 mm in diameter) and small (1–3 mm) follicles responded similarly to gonadotrophins. Granulosa cells from small follicles failed to respond to stimulation by HCG. FSH, however, consistently increased cAMP production in comparison with controls or cells treated with HCG. Granulosa cells of large follicles responded to both HCG and FSH.

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