scholarly journals Resveratrol inhibits Ca2+ signals and aggregation of platelets

2020 ◽  
Vol 25 (1) ◽  
Author(s):  
Mikio Marumo ◽  
Kazumi Ekawa ◽  
Ichiro Wakabayashi
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Human Platelets ◽  
Fluorescence Method ◽  
Transient Increase ◽  
Light Transmittance ◽  
Inhibit Platelet Aggregation ◽  
Free Medium ◽  
Intracellular Ca ◽  
Aggregation Of Platelets

Abstract Background Resveratrol has been shown to inhibit platelet aggregation. However, the mechanism for this action of resveratrol remains to be clarified. The purpose of this study was to elucidate the Ca2+-related mechanism for the inhibitory action of resveratrol on platelet aggregation. Methods Ca2+ entry and subsequent aggregation of human platelets induced by different stimulants including thrombin, thapsigargin, and 1-oleoyl-2-acetylglycerol (OAG) were measured by the fluorescence method and light transmittance method, respectively. Each stimulant was added to a nominally Ca2+-free medium containing platelets, and then CaCl2 was added to the medium to induce Ca2+ influx into platelets. Results Thapsigargin-induced Ca2+ entry into platelets and subsequent platelet aggregation were significantly inhibited in the presence of resveratrol at 6.25 μM or higher concentrations, while OAG-induced Ca2+ entry and subsequent platelet aggregation were not affected by resveratrol at concentrations up to 50 μM. In the nominally Ca2+-free medium, thrombin induced a small transient increase in intracellular Ca2+ concentrations, which was attenuated in the presence of resveratrol at 12.5 μM or higher concentrations. Thrombin-induced Ca2+ entry into platelets and subsequent platelet aggregation were significantly inhibited in the presence of resveratrol at 12.5 μM or higher concentrations. Conclusions The results suggest that resveratrol inhibits thrombin-induced platelet aggregation through decreasing Ca2+ release from its stores and inhibiting store-operated Ca2+ influx into platelets.

MODE OF ACTION OF A NOVEL ANTI-PLATELET AGENT (E-5510)

1987 ◽  
Author(s):  
T Saeki ◽  
K HARADA ◽  
T Youshimura ◽  
Y Nakamura ◽  
T Fujimori ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Human Platelets ◽  
Cyclooxygenase Inhibitor ◽  
Inhibit Platelet Aggregation ◽  
Camp Content ◽  
Anti Platelet Agent ◽  
Intracellular Ca ◽  
Dose Dependent Fashion ◽  
Dose Dependent

A novel anti-platelet agent, 4-cyano-5,5-bis(4-methoxy-phenyl)-4-pentenoic acid(E-5510), has been shown to inhibit platelet aggregation and secretion induced by thrombin as well as by other inducers such as ADP, collagen and PAF. Although E-5510 can act as a cyclooxygenase inhibitor,inhibition of cyclooxygenase may not be the primary mode of action since this compound effectively inhibits thrombin-induced platelet activation. In this paper, effects^of E-5510 on arachidonic acid (AA) metabolism, intracellular Ca++ and cAMP in human platelets are examined.(1) Effect on AA metabolism. Platelets prelabeled with [14 C]-AA were stimulated with thrombin. E-5510 inhibited not only thromboxane A2 and HHT generation but also 12-HETE generation in a dose-dependent fashion. The total AA released was also reduced by E-5510. An almost 50% reduction was obtained by 10 uM of this compound. On the other hand, a cyclooxygenase inhibitor such as U-53059 increased 12-HETE generation in a dose-dependent fashion. In addition to the inhibition of AA metabolism, E-5510 exerted inhibitory effects on phosphatidic acidgeneration, which suggests the possible inhibition of phospholipase C activity by this compound.(2) Effect on intracellular Ca++ and protein phosphorylation. Intracellular Ca++ mobilization was examined using Fura-2 loaded human platelet suspension. The increase in intracellular Ca induced by thrombin was inhibited by E-5510 and the increase in phosphorylation of 40 K protein was also suppressed by this compound after the stimulation of human platelets by thrombin.(3) Effect on cAMP. Platelets were incubated with 10-100 uM of E-5510 and the cAMP content in human platelets was measured. E-5510 increased the cAMP content in a dose-dependent fashion. In platelet homogenate, E-5510 inhibited phosphodiesterase activity with an IC50 of 10 uM.These results suggest that E-5510 may inhibit platelet aggregation and secretion through the multiple modes of action, such as inhibition of phospholipase C, phosphodiesterase and cyclooxygenase, in the process of platelet activation.

Reaction of Acetaldehyde with Human Platelets

1992 ◽  
Vol 67 (01) ◽  
pp. 126-130 ◽  
Author(s):  
Olivier Spertini ◽  
Jacques Hauert ◽  
Fedor Bachmann
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Reaction Medium ◽  
Human Platelets ◽  
Membrane Glycoproteins ◽  
Neutral Ph

SummaryPlatelet function defects observed in chronic alcoholics are not wholly explained by the inhibitory action of ethanol on platelet aggregation; they are not completely reproduced either in vivo by short-term ethanol perfusion into volunteers or in vitro by the addition of ethanol to platelet-rich plasma. As acetaldehyde (AcH) binds to many proteins and impairs cellular activities, we investigated the effect of this early degradation product of ethanol on platelets. AcH formed adducts with human platelets at neutral pH at 37° C which were stable to extensive washing, trichloracetic acid hydrolysis and heating at 100° C, and were not reduced by sodium borohydride. The amount of platelet adducts formed was a function of the incubation time and of the concentration of AcH in the reaction medium. At low AcH concentrations (<0.2 mM), platelet bound AcH was directly proportional to the concentration of AcH in the reaction medium. At higher concentrations (≥0.2 mM), AcH uptake by platelets tended to reach a plateau. The amount of adducts was also proportional to the number of exposures of platelets to pulses of 20 pM AcH.AcH adducts formation severely impaired platelet aggregation and shape change induced by ADP, collagen and thrombin. A positive correlation was established between platelet-bound AcH and inhibition of aggregation.SDS-PAGE analysis of AcH adducts at neutral pH demonstrated the binding of [14C]acetaldehyde to many platelet proteins. AcH adduct formation with membrane glycoproteins, cytoskeleton and enzymes might interfere with several steps of platelet activation and impair platelet aggregation.This in vitro study shows that AcH has a major inhibitory action on platelet aggregation and may account for the prolonged ex vivo inhibition of aggregation observed in chronic alcoholics even in the absence of alcoholemia.

scholarly journals Histidine-rich glycoprotein is present in human platelets and is released following thrombin stimulation

Blood ◽  
1983 ◽  
Vol 62 (5) ◽  
pp. 1016-1021 ◽  
Author(s):  
LL Leung ◽  
PC Harpel ◽  
RL Nachman ◽  
EM Rabellino
Keyword(s):  
Bone Marrow ◽  
Platelet Aggregation ◽  
Divalent Cations ◽  
Human Platelets ◽  
Serotonin Release ◽  
Enzyme Linked Immunosorbent Assay ◽  
Immunochemical Analysis ◽  
Inhibit Platelet Aggregation ◽  
Specific Enzyme ◽  
High Affinity

Abstract Histidine-rich glycoprotein, and alpha 2-glycoprotein in human plasma, has been shown to interact with heparin, with the high-affinity lysine- binding site of plasminogen, with divalent cations, and is associated with the rosette formation between erythrocytes and lymphocytes. A specific enzyme-linked immunosorbent assay for histidine-rich glycoprotein has been developed and used to demonstrate that histidine- rich glycoprotein is present in human platelets. Histidine-rich glycoprotein was detected and quantified in detergent extracts of washed human platelets, with a mean level of 371 ng/10(9) platelets. Plasma histidine-rich glycoprotein, either in the platelet suspending medium or on the surface of the platelets, accounted for less than 3.4% of the detectable platelet histidine-rich glycoprotein. Histidine-rich glycoprotein was also demonstrated in human bone marrow megakaryocytes by immunofluorescence. The extent of histidine-rich glycoprotein release from platelets was dependent on the thrombin dose and correlated directly with the extent of serotonin release. The platelet and plasma histidine-rich glycoprotein were similar by immunochemical analysis. Anti-histidine-rich glycoprotein IgG did not inhibit platelet aggregation. Histidine-rich glycoprotein released by platelets following thrombin stimulation may play a significant role in modulating inflammatory events in the microenvironment of the platelet plug.

Effect of Heparin on Aggregation, Release Reaction and Thromboxane A2synthesis in Human Platelets

1979 ◽  
Author(s):  
H.Y.K. Chuang ◽  
S.F. Mohammad ◽  
R.G. Mason
Keyword(s):  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Thromboxane A2 ◽  
Rabbit Aorta ◽  
Human Platelets ◽  
Appreciable Effect ◽  
Layer Chromatography ◽  
Aggregation Of Platelets ◽  
Platelet Functions

Studies on the effect of heparin on platelet functions have resulted in conflicting observations: heparin has been reported to cause aggregation of platelets, potentiate aggregation induced by various aggregating agents, or cause inhibition of aggregation. Using paritally purified heparin (beef lung or porcine mucosa) we observed that addition of heparin to citrated platelet rich plasma(C-PRP)potentiated the aggregation of platelets induced by ADP, epinephrine, or arachidonic acid. Presence of heparin in C-PRP results in complete inhibition of thrombin induced effects and partial inhibition of platelet aggregation induced by collagen. Presence of heparin in C-PRP also resulted in release of significantly higher concentrations of 14C-serotonin when platelets were challenged by appropriate aggregating agents. Those concentrations of heparin that resulted in potentiation of aggregation had no appreciable effect on c-AiMP or c-GMP levels of platelets. However, the presence of heparin results in a significant elevation of thromboxane A2 as determined by contraction of rabbit aorta or after conversion to thromboxane B2 by thin layer chromatography. These observations are of interest since increased production of thromboxane A2 in the presence of heparin may explain in part, the potentiation of platelet aggregation in vitro or thrombocytopenia observed frequently in patients receiving heparin intravenously Supported in part by grants HL22583 & 20679 from NHLBI of NIH.

Mechanisms Involved in the Antiplatelet Activity of Midazolam in Human Platelets

2002 ◽  
Vol 96 (3) ◽  
pp. 651-658 ◽  
Author(s):  
Joen R. Sheu ◽  
George Hsiao ◽  
Hsiung N. Luk ◽  
Yi W. Chen ◽  
Ta L. Chen ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Platelet Aggregation ◽  
Protein Kinase ◽  
Thromboxane A2 ◽  
Human Platelets ◽  
Antiplatelet Activity ◽  
Phosphoinositide Breakdown ◽  
Kinase C ◽  
Inhibitory Mechanisms ◽  
Intracellular Ca

Background Midazolam is widely used as a sedative and anesthetic induction agent. The aim of this study was to systematically examine the inhibitory mechanisms of midazolam in platelet aggregation. Methods The inhibitory mechanisms of midazolam in platelet aggregation were explored by means of analysis of the platelet glycoprotein IIb-IIIa complex, phosphoinositide breakdown, intracellular Ca+2 mobilization, measurement of membrane fluidity, thromboxane B2 formation, and protein kinase C activity. Results In this study, midazolam dose-dependently (6-26 microm) inhibited platelet aggregation in human platelets stimulated by agonists. Midazolam also dose-dependently inhibited phosphoinositide breakdown and intracellular Ca+2 mobilization in human platelets stimulated by collagen. Midazolam (6-26 mum) significantly inhibited thromboxane A2 formation stimulated by collagen in human platelets. Moreover, midazolam (15 and 26 mum) dose-dependently decreased the fluorescence of platelet membranes tagged with diphenylhexatriene. Rapid phosphorylation of a platelet protein of Mr 47,000 (P47), a marker of protein kinase C activation, was triggered by collagen (2 microg/ml). This phosphorylation was markedly inhibited by midazolam (26 microm). Conclusions These results indicate that the antiplatelet activity of midazolam may be involved in the following pathways: the effects of midazolam may initially be caused by induction of conformational changes in platelet membrane, leading to a change in the activity of phospholipase C, and subsequent inhibition of phosphoinositide breakdown and thromboxane A2 formation, thereby leading to inhibition of both intracellular Ca+2 mobilization and phosphorylation of P47 protein.

scholarly journals Platelet activation by immobilized monoclonal antibody: evidence for a CD9 proximal signal

Blood ◽  
1991 ◽  
Vol 78 (7) ◽  
pp. 1753-1759
Author(s):  
L Griffith ◽  
J Slupsky ◽  
J Seehafer ◽  
L Boshkov ◽  
AR Shaw
Keyword(s):  
Platelet Aggregation ◽  
Hla Class I ◽  
Human Platelets ◽  
Dense Granule ◽  
Polystyrene Latex ◽  
Cross Linking ◽  
Latex Beads ◽  
Dose Dependent ◽  
Aggregation Of Platelets ◽  
Granule Release

Anti-CD9 monoclonal antibodies (MoAbs) are reported to activate human platelets through stimulation of the Fc gamma II receptor. We show here that nonstimulatory F(ab')2 fragments of the anti-CD9 MoAb 50H.19 induce dense-granule release and dose-dependent platelet aggregation when attached to polystyrene latex beads. Cross-linking F(ab')2 fragments of MoAb 50H.19 by F(ab')2 fragments of goat anti-mouse IgG does not result in platelet aggregation unless the second antibody is bound to latex beads, indicating that immobilization, and not cross- linking of the stimulus, is critical to the initiation of the CD9 signal. In contrast, F(ab')2 fragments of the second antibody readily induce the aggregation of platelets treated with the anti-Fc gamma II receptor MoAb IV.3. Immobilization of MoAb per se is insufficient to induce an activation signal because intact and F(ab')2 fragments of nonstimulatory MoAb directed to glycoprotein Ib and HLA class I do not become stimulatory when attached to beads. CD9-induced activation requires cytoskeletal rearrangement because it is inhibited by cytochalasin B. Aggregation is blocked by inhibitors of the thromboxane pathway, indicating that CD9 activates phospholipase C indirectly through prior activation of phospholipase A2.\

Inhibition of ADP-Induced Platelet Aggregation by Adenosine Tetraphosphate

1976 ◽  
Vol 36 (02) ◽  
pp. 388-391 ◽  
Author(s):  
Margaret J. Harrison ◽  
R Brossmer
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Platelet Rich Plasma ◽  
Release Reaction ◽  
Induced Aggregation ◽  
Aggregation Of Platelets

SummaryIn contrast to previous reports, highly purified adenosine tetraphosphate (AP4) does not induce the aggregation of platelets but inhibits the aggregation and release reaction in platelet-rich plasma promoted by ADP. The inhibitory action of AP4 on the aggregation by ADP is compared with that of AMP and ATP. The data presented suggest a competitive manner of inhibition of the ADP-induced aggregation by AP4.

Potentiating Effect of Adenosine on Other Inhibitors of Platelet Aggregation

1972 ◽  
Vol 27 (02) ◽  
pp. 252-262 ◽  
Author(s):  
M. Murakami ◽  
K. Odake ◽  
M. Takase ◽  
K. Yoshino
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Prostaglandin E1 ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
The Other ◽  
Other Hand ◽  
Adp Release

SummaryAdenosine was rapidly incorporated into human platelets, and the inhibitory effect of adenosine on platelet aggregation was correlated with the incorporation process. Adenosine potentiated the inhibitory action of other inhibitors, such as dipyridamole, prostaglandin E1 and Y-3642. The inhibition of aggregation was associated with the preservation of platelet adenine nucleotides and the prevention of ADP release. On the other hand, the radioactive adenine nucleotide pattern of platelets was not substantially affected by inhibitors. The relation of inhibition of aggregation with ADP release was discussed.

Effects of Lead Acetate on Platelet Aggregation, Ultrastructure and Serotonin Release

1971 ◽  
Vol 26 (03) ◽  
pp. 455-466 ◽  
Author(s):  
R. B Davis ◽  
G. C Holtz
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Lead Acetate ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
Blood Platelet ◽  
Human Platelets ◽  
Serotonin Release ◽  
Aggregation Of Platelets

SummaryThe effects of lead on blood platelet function and ultrastructure have been investigated. Lead acetate was injected intravenously in 27 rats and was added to rat and human platelet rich plasma in vitro. In vitro studies showed that concentrations of 2.5 × 10-3 M lead acetate reduced or blocked aggregation of rat and human platelets by adenosine diphosphate, collagen, and thrombin. Radioactive serotonin release from human platelets was inhibited by 10-4 M lead acetate. One hour after the injection of lead, platelet aggregation by thrombin was reduced, but platelet aggregation by adenosine diphosphate and collagen showed little change. Three days after lead, aggregation of platelets by collagen and thrombin was blocked and aggregation by adenosine diphosphate reduced. Thrombocytopenia was present 4 days after intravenous lead acetate. Electron micrographs of platelets showed that the mean number of mitochondria per platelet was increased, whereas alpha granules were reduced. Dense bodies were not significantly changed. Lead acetate affects platelet function in concentrations reported in human bone marrow in lead poisoning, and may relate to the binding of free sulfhydryl groups by lead.

scholarly journals Platelet activation by immobilized monoclonal antibody: evidence for a CD9 proximal signal

Blood ◽  
1991 ◽  
Vol 78 (7) ◽  
pp. 1753-1759 ◽  
Author(s):  
L Griffith ◽  
J Slupsky ◽  
J Seehafer ◽  
L Boshkov ◽  
AR Shaw
Keyword(s):  
Platelet Aggregation ◽  
Hla Class I ◽  
Human Platelets ◽  
Dense Granule ◽  
Polystyrene Latex ◽  
Cross Linking ◽  
Latex Beads ◽  
Dose Dependent ◽  
Aggregation Of Platelets ◽  
Granule Release

Abstract Anti-CD9 monoclonal antibodies (MoAbs) are reported to activate human platelets through stimulation of the Fc gamma II receptor. We show here that nonstimulatory F(ab')2 fragments of the anti-CD9 MoAb 50H.19 induce dense-granule release and dose-dependent platelet aggregation when attached to polystyrene latex beads. Cross-linking F(ab')2 fragments of MoAb 50H.19 by F(ab')2 fragments of goat anti-mouse IgG does not result in platelet aggregation unless the second antibody is bound to latex beads, indicating that immobilization, and not cross- linking of the stimulus, is critical to the initiation of the CD9 signal. In contrast, F(ab')2 fragments of the second antibody readily induce the aggregation of platelets treated with the anti-Fc gamma II receptor MoAb IV.3. Immobilization of MoAb per se is insufficient to induce an activation signal because intact and F(ab')2 fragments of nonstimulatory MoAb directed to glycoprotein Ib and HLA class I do not become stimulatory when attached to beads. CD9-induced activation requires cytoskeletal rearrangement because it is inhibited by cytochalasin B. Aggregation is blocked by inhibitors of the thromboxane pathway, indicating that CD9 activates phospholipase C indirectly through prior activation of phospholipase A2.\

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