scholarly journals Increased expression of procoagulant activity on the surface of human platelets exposed to heavy-metal compounds

1995 ◽  
Vol 308 (1) ◽  
pp. 15-21 ◽  
Author(s):  
C A Goodwin ◽  
C P D Wheeler-Jones ◽  
S Namiranian ◽  
S Bokkala ◽  
V V Kakkar ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Procoagulant Activity ◽  
Ionophore A23187 ◽  
Dependent Manner ◽  
Anionic Phospholipid ◽  
Metal Compounds ◽  
Platelet Surface ◽  
Thrombin Formation

One of the essential roles for platelets in haemostasis is in the potentiation of blood clotting due to the contribution of anionic phospholipid from the surface of the cells, as an essential cofactor to the proteolytic reactions of coagulation (platelet procoagulant activity). Only a limited number of agonists are known to initiate platelet procoagulant activity. In this study the rate of thrombin formation on the platelet surface was observed to increase in a dose-dependent manner upon treatment of washed platelets with heavy-metal compounds. Unlike the immediate increase observed upon treatment of platelets with calcium ionophore, A23187, the change due to these agents was progressive, approaching a maximum after 10 min. The maximum-fold acceleration of the rate of thrombin formation compared with control platelets was calculated for HgCl2 (56-fold), AgNO3 (42-fold) phenylmercuriacetate (24-fold) and thimerosal (14-fold), compared with 70-fold observed for calcium ionophore. The increase in procoagulant activity due to HgCl2 coincided with a large increase in intracellular calcium and phosphorylation of 22 and 45 kDa proteins. It is considered that the mechanism responsible for the increase in procoagulant activity is exposure of anionic phospholipids. This was detected by a 2-fold increase in the binding of 125I-annexin V upon addition of HgCl2, compared with resting platelets (3-fold on treatment of platelets with calcium ionophore). In contrast to the generation of activity by A23187 and other known agonists of this reaction, heavy-metal compounds appeared to cause little or no release of microparticles from the platelet surface. Since HgCl2 did not cause aggregation of platelets or significant release of serotinin, these findings may give further support to the need for exposure and ligation of glycoprotein IIb:IIIa for vesiculization to occur. Treatment of platelets with heavy metals may constitute a new approach to investigating the early changes in the cell membrane which lead to increased expression of anionic phospholipid.

scholarly journals Complement proteins C5b-9 stimulate procoagulant activity through platelet prothrombinase

Blood ◽  
1986 ◽  
Vol 68 (4) ◽  
pp. 875-880 ◽  
Author(s):  
T Wiedmer ◽  
CT Esmon ◽  
PJ Sims
Keyword(s):  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Procoagulant Activity ◽  
Ionophore A23187 ◽  
Factor V ◽  
Platelet Factor ◽  
Platelet Surface ◽  
Prothrombinase Complex ◽  
Factor Va ◽  
Exogenous Factors

Abstract The capacity of platelets treated with nonlytic concentrations of the C5b-9 proteins to catalyze prothrombin activation and thereby trigger clot formation has been investigated. When suspended in the presence of exogenous factors Xa and Va, gel-filtered platelets treated with purified C5b-9 proteins catalyzed prothrombin to thrombin conversion at rates up to tenfold above controls, and exceeded by up to fourfold the prothrombinase activity observed for thrombin-stimulated platelets. In the absence of added factor Va, C5b-9 assembly on the platelet surface significantly shortened the lag period before prothrombinase expression that was observed for untreated platelets and increased the maximum catalytic rate of thrombin formation. A comparison with other platelet stimuli revealed that the C5b-9-induced activation of platelet prothrombinase closely paralleled the effects mediated by calcium ionophore A23187. Our data suggest that the C5b-9 proteins promote the release of platelet factor V and the assembly of the prothrombinase complex, thereby potentiating the effects of thrombin on the activation of prothrombinase. Membrane assembly of the C5b-9 proteins was also observed to markedly accelerate the rate of platelet-catalyzed plasma clotting, suggesting a direct link between C5b-9-mediated prothrombinase activation and procoagulant activity accompanying immunologic damage to the platelet.

scholarly journals Complement proteins C5b-9 stimulate procoagulant activity through platelet prothrombinase

Blood ◽  
1986 ◽  
Vol 68 (4) ◽  
pp. 875-880 ◽  
Author(s):  
T Wiedmer ◽  
CT Esmon ◽  
PJ Sims
Keyword(s):  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Procoagulant Activity ◽  
Ionophore A23187 ◽  
Factor V ◽  
Platelet Factor ◽  
Platelet Surface ◽  
Prothrombinase Complex ◽  
Factor Va ◽  
Exogenous Factors

The capacity of platelets treated with nonlytic concentrations of the C5b-9 proteins to catalyze prothrombin activation and thereby trigger clot formation has been investigated. When suspended in the presence of exogenous factors Xa and Va, gel-filtered platelets treated with purified C5b-9 proteins catalyzed prothrombin to thrombin conversion at rates up to tenfold above controls, and exceeded by up to fourfold the prothrombinase activity observed for thrombin-stimulated platelets. In the absence of added factor Va, C5b-9 assembly on the platelet surface significantly shortened the lag period before prothrombinase expression that was observed for untreated platelets and increased the maximum catalytic rate of thrombin formation. A comparison with other platelet stimuli revealed that the C5b-9-induced activation of platelet prothrombinase closely paralleled the effects mediated by calcium ionophore A23187. Our data suggest that the C5b-9 proteins promote the release of platelet factor V and the assembly of the prothrombinase complex, thereby potentiating the effects of thrombin on the activation of prothrombinase. Membrane assembly of the C5b-9 proteins was also observed to markedly accelerate the rate of platelet-catalyzed plasma clotting, suggesting a direct link between C5b-9-mediated prothrombinase activation and procoagulant activity accompanying immunologic damage to the platelet.

Immunologic mast cell-mediated responses and histamine release are attenuated by heparin

1992 ◽  
Vol 73 (3) ◽  
pp. 1093-1101 ◽  
Author(s):  
J. Lucio ◽  
J. D'Brot ◽  
C. B. Guo ◽  
W. M. Abraham ◽  
L. M. Lichtenstein ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Histamine Release ◽  
Immunoglobulin E ◽  
Specific Antigen ◽  
Calcium Ionophore ◽  
Intradermal Injection ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Dependent Manner

Heparin has been shown to act as a competitive inhibitor of inositol 1,4,5-triphosphate (InsP3) receptors in various cell types. Because InsP3 is one of the second messengers involved in stimulus-secretion coupling in mast cells, it is possible that heparin may inhibit mast cell-mediated reactions. Therefore, in allergic sheep, we tested this hypothesis in two mast cell-mediated reactions induced by immunologic and nonimmunologic stimuli: immediate cutaneous reaction (ICR) and acute bronchoconstrictor response (ABR). In 12 sheep allergic to Ascaris suum antigen, the surface area of the skin wheal was determined 20 min after intradermal injection (0.05 ml) of increasing concentrations of specific antigen, compound 48/80, and histamine, without and after pretreatment with heparin (100, 300, or 1,000 U/kg i.v.). Antigen, compound 48/80, and histamine produced concentration-dependent increases in ICR. Heparin “partially” inhibited the ICR to antigen and compound 48/80 in a dose-dependent manner without modifying the ICR to histamine. The heparin preservative benzyl alcohol was ineffective. In 11 additional sheep, specific lung resistance was measured before and after inhalation challenges with antigen, compound 48/80, and histamine without and with aerosol heparin pretreatment (1,000 U/kg). Heparin blocked the antigen- and compound 48/80-induced bronchoconstriction without modifying the airway effects of histamine. In isolated human uterine mast cells, heparin inhibited the anti-immunoglobulin E- but not the calcium ionophore- (A23187) induced histamine release. These data suggest that heparin inhibits the ICR and ABR induced by stimuli that produce immunologic and nonimmunologic mast cell degranulation without attenuating the effects of histamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet microparticle membranes have 50- to 100-fold higher specific procoagulant activity than activated platelets

2007 ◽  
Vol 97 (03) ◽  
pp. 425-434 ◽  
Author(s):  
Dmitry Kireev ◽  
Nadezhda Popenko ◽  
Aleksei Pichugin ◽  
Mikhail Panteleev ◽  
Olga Krymskaya ◽  
...  
Keyword(s):  
Blood Platelets ◽  
Calcium Ionophore ◽  
Coagulation Factors ◽  
In Vitro Models ◽  
Calcium Ionophore A23187 ◽  
Procoagulant Activity ◽  
Ionophore A23187 ◽  
Factor X ◽  
Activated Platelets

SummaryPlatelet microparticles (PMPs) are small vesicles released from blood platelets upon activation. The procoagulant activity of PMPs has been previously mainly characterized by theirability to bind coagulation factors VIII and Va in reconstructed systems. It can be supposed that PMPs can contribute to the development of thrombotic complications in the pathologic states associated with the increase of their blood concentration. In this study we compared procoagulant properties of calcium ionophore A23187-activated platelets and PMPs using several in-vitro models of hemostasis. Surface densities of phosphatidylserine, CD61, CD62P and factor X bound per surface area unit were determined by flow cytometry. They were 2.7-, 8.4-, 4.3-, and 13-fold higher for PMPs than for activated platelets, respectively. Spatial clot growth rate (Vclot) in the reaction-diffus ion experimental model and endogenous thrombin potential (ETP) were determined in plasma, which was depleted of phospholipid cell surfaces by ultra-centrifugation and supplemented with activated platelets or PMPs at different concentrations. Both Vcllot and ETP rapidly increased with the increase of PMP or platelet concentration until saturation was reached. The plateau values of Vclot and ETP for activated platelets and PMPs were similar. In both assays, the procoagulant activity of one PMP was almost equal to that of one activated platelet despite at least two-orders-of-magnitude difference in their surface areas. This suggests that the PMP surface is approximately 50- to 100-fold more procoagulant than the surface of activated platelets.

Down Regulation of Thrombin Procoagulant Activity by Prothrombin Activation Fragment 1.2.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1946-1946
Author(s):  
Swapan K. Dasgupta ◽  
Perumal Thiagarajan
Keyword(s):  
Active Site ◽  
Procoagulant Activity ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Anionic Phospholipid ◽  
Platelet Surface ◽  
Amino Terminal ◽  
Induced Aggregation ◽  
Kringle 2 ◽  
Prothrombin Activation

Abstract Prothrombin is the precursor of thrombin, the central enzyme in coagulation. Under physiological condition, prothrombin activation catalyzed by the fully assembled prothrombinase complex via an ordered, sequential reaction with primary cleavage at Arg320-lle321 followed by the second cleavage at Arg271-Thr272, forming fragment 1.2 and thrombin. The fragment 1.2 contains the amino-terminal gla domain and the two kringle domains. It has been shown that the kringle 2 domain in fragment 2 can bind to the exosite II of thrombin and inhibit allosterically its activity by inducing conformational changes at the active site. Nascent thrombin that is generated on platelet surface will remains non-covalenty bound to fragment 1.2 by kringle 2-exosite II interaction. To determine whether this interaction can modulate thrombin activity, we tested the effect of anionic phospholipid-bound fragment 1.2 (0–10 μM) on thrombin clotting activity. Phospholipid-bound fragment 1.2 inhibited fibrinogen clotting in a concentration-dependent manner but had no significant effect on esterase activity towards S2238 (D-Phe-Pip-Arg-pNA.2HCI) suggesting a competitive inhibition of fibrinogen binding. We also labeled thrombin at the active site with fluorescein-FPRCK (5-fluorescein-D-Phe-Pro-Arg chloromethyl-ketone) and monitored fluorescence changes following fragment 1.2 binding in a spectrofluorometer. Anionic phospholipid-bound fragment 1.2 induced changes in the active site similar to fragment 2 with half maximal effect at ~8 μM. We tested the effect of fragment 1.2 on fluorescein-FPR thrombin binding to platelets. Fragment 1.2 inhibited thrombin binding to platelet. Consistent with these findings fragment 1.2 inhibited thrombin-induced aggregation of gel filtered platelets in a concentration-dependant manner. These results suggest that membrane-bound prothrombin fragment 1.2 may play an important role in hemostasis by down regulating thrombin procoagulant activity because of its interaction with exosite 2.

scholarly journals Defective Ca(2+)-induced microvesiculation and deficient expression of procoagulant activity in erythrocytes from a patient with a bleeding disorder: a study of the red blood cells of Scott syndrome

Blood ◽  
1992 ◽  
Vol 79 (2) ◽  
pp. 380-388 ◽  
Author(s):  
EM Bevers ◽  
T Wiedmer ◽  
P Comfurius ◽  
SJ Shattil ◽  
HJ Weiss ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Calcium Ionophore ◽  
Coagulation Factors ◽  
Calcium Ionophore A23187 ◽  
Bleeding Disorder ◽  
Procoagulant Activity ◽  
Ionophore A23187 ◽  
Factor Va ◽  
Resealed Ghosts

The erythrocytes from a patient with Scott syndrome, a bleeding disorder characterized by an isolated defect in expression of platelet procoagulant activity, have been studied. When incubated with the calcium ionophore A23187, Scott syndrome red blood cells (RBCs) expressed less than 10% of the prothrombinase (enzyme complex of coagulation factors Va and Xa) activity of A23187-treated RBCs obtained from normal controls. Consistent with the results from enzyme assay, the ionophore-treated Scott syndrome erythrocytes exhibited diminished membrane vesiculation and decreased exposure of membrane binding sites for factor Va compared with identically treated controls. When examined by scanning electron microscopy, untreated Scott syndrome RBCs were indistinguishable from normal cells. After incubation with A23187, however, the morphology of Scott syndrome RBCs contrasted markedly from normal erythrocytes. Whereas the Ca2+ ionophore induced marked echinocytosis and spiculation of normal RBCs, Scott syndrome RBCs remained mostly discoid under these conditions, with only an occasional echinocyte-like cell observed. These aberrant responses to intracellular Ca2+ were also observed for resealed ghosts prepared from Scott syndrome erythrocytes, indicating that they are related to a defect in the membrane or membrane-associated cytoskeleton. The finding that the erythrocytes of this patient share many of the membrane abnormalities reported previously for Scott syndrome platelets suggests that this defect is common to both cell lines and involves a membrane component required for vesicle formation and for expression of prothrombinase sites.

scholarly journals von Willebrand factor is present on the surface of platelets stimulated in plasma by ADP

Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1362-1366
Author(s):  
B Adelman ◽  
P Carlson ◽  
P Powers
Keyword(s):  
Binding Site ◽  
Von Willebrand Factor ◽  
Platelet Rich Plasma ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Surface Binding ◽  
Platelet Surface ◽  
Von Willebrand ◽  
Willebrand Factor

von Willebrand factor (vWf) can bind to glycoprotein (GP) IIb/IIIa on activated platelets. The significance of this interaction is unclear, however, because it has not been possible to detect vWf binding to GPIIb/IIIa on platelets stimulated in plasma. We have developed an indirect, flow cytometry assay that uses fluorescein-labeled antibodies to detect vWf and fibrinogen on platelets. Using this assay, we found vWf on the surface of platelets stimulated in plasma by ADP. The number of platelets that bound vWf increased in proportion to ADP concentration and incubation time. Washed platelets in a protein-free buffer activated by 1 mumol/L calcium ionophore A23187 or 10 mumol/L ADP also bound vWf, suggesting that we were detecting surface binding of alpha-granule-derived vWf. Monoclonal antibodies against the vWf binding site on GPIb (6D1) and the vWf and fibrinogen binding sites on GPIIb/IIIa (LJP5 and LJ-CP8, respectively) were used to characterize the mechanism of vWf binding to stimulated platelets. Ristocetin- induced binding of vWf was inhibited by 6D1, and ADP-induced binding of fibrinogen was inhibited by LJ-CP8. None of these antibodies inhibited ADP-induced vWf binding. Aspirin and prostaglandin E1 also inhibited ADP-induced binding of vWf in platelet-rich plasma. During platelet activation in plasma, vWf derived from alpha-granules becomes bound to the platelet surface possibly being transferred already associated with a binding site.

Ca2+-dependent Activation of the 33-kDa Protein Kinase Transmits Thrombin Receptor Signals in Human Platelets

1996 ◽  
Vol 76 (03) ◽  
pp. 439-443 ◽  
Author(s):  
Masaru Ido ◽  
Shinya Kato ◽  
Hiroyuki Ogawa ◽  
Kenji Hayashi ◽  
Yoshihiro Komada ◽  
...  
Keyword(s):  
Kinase Inhibitor ◽  
Calcium Ionophore ◽  
Structural Analog ◽  
Human Platelets ◽  
Calcium Ionophore A23187 ◽  
Similar Degree ◽  
Ionophore A23187 ◽  
Dependent Manner ◽  
Serine Threonine Kinase ◽  
Acetoxymethyl Ester

SummaryThrombin stimulation induces a dramatic increase in the activity of the 33-kDa serine/threonine kinase (PK33) in human platelets (10). The Arg-Gly-Asp (RGD) peptide, an inhibitor of the thrombin-mediated aggregation of platelets, did not affect the PK33 activation induced by thrombin suggesting that the activation of this kinase occurs independently from platelet aggregation. To identify a potential role of Ca2+ and calmodulin in the regulation of PK33, the effect of several Ca2+/calmodulin inhibitors on the thrombin-induced activation of PK33 was assessed using denaturation/renaturation method. Pretreatment of platelets with EGTA decreased the maximum PK33 activity induced by thrombin. The chelation of both the extra- and the intracellular Ca2+ by EGTA and by acetoxymethyl ester of 5,5′ -dimethyl-bis-(<9-aminophen-oxy) ethane-N,N,N′,N′-tetraacetic acid (BAPTA-AM) decreased further the PK33 activation by thrombin. Preincubation of platelets with the anticalmodulin agent, N-(4-aminobutyl)-5-chloro-2-naphtha-lenesulfonamide (W13), inhibited markedly the activation of PK33 by thrombin, whereas the inactive structural analog N-(4-aminobutyl)-2-naphthalenesulfonamide (W12) and the myosin light chain kinase inhibitor 1 -(5-chloronaphthalene-1 -sulfonyl)-1 H-hexahydro-1,4-diaze-pine (ML9) showed very weak inhibitory effects. Treatment of resting platelets with the calcium ionophore, A23187, activated PK33 in a dose-dependent manner; phorbol 12-myristate 13-acetate enhanced this effect. However, the two foregoing agents did not induce similar degree of PK33 activities as thrombin. These results indicate that the activation of PK33 is independent of the formation of the GPIIb/IIIa-fibrinogen complex and that it might be regulated by a Ca2+-dependent pathway.

scholarly journals Defective Ca(2+)-induced microvesiculation and deficient expression of procoagulant activity in erythrocytes from a patient with a bleeding disorder: a study of the red blood cells of Scott syndrome

Blood ◽  
1992 ◽  
Vol 79 (2) ◽  
pp. 380-388 ◽  
Author(s):  
EM Bevers ◽  
T Wiedmer ◽  
P Comfurius ◽  
SJ Shattil ◽  
HJ Weiss ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Calcium Ionophore ◽  
Coagulation Factors ◽  
Calcium Ionophore A23187 ◽  
Bleeding Disorder ◽  
Procoagulant Activity ◽  
Ionophore A23187 ◽  
Factor Va ◽  
Resealed Ghosts

Abstract The erythrocytes from a patient with Scott syndrome, a bleeding disorder characterized by an isolated defect in expression of platelet procoagulant activity, have been studied. When incubated with the calcium ionophore A23187, Scott syndrome red blood cells (RBCs) expressed less than 10% of the prothrombinase (enzyme complex of coagulation factors Va and Xa) activity of A23187-treated RBCs obtained from normal controls. Consistent with the results from enzyme assay, the ionophore-treated Scott syndrome erythrocytes exhibited diminished membrane vesiculation and decreased exposure of membrane binding sites for factor Va compared with identically treated controls. When examined by scanning electron microscopy, untreated Scott syndrome RBCs were indistinguishable from normal cells. After incubation with A23187, however, the morphology of Scott syndrome RBCs contrasted markedly from normal erythrocytes. Whereas the Ca2+ ionophore induced marked echinocytosis and spiculation of normal RBCs, Scott syndrome RBCs remained mostly discoid under these conditions, with only an occasional echinocyte-like cell observed. These aberrant responses to intracellular Ca2+ were also observed for resealed ghosts prepared from Scott syndrome erythrocytes, indicating that they are related to a defect in the membrane or membrane-associated cytoskeleton. The finding that the erythrocytes of this patient share many of the membrane abnormalities reported previously for Scott syndrome platelets suggests that this defect is common to both cell lines and involves a membrane component required for vesicle formation and for expression of prothrombinase sites.

scholarly journals The Role of Rhodomyrtus tomentosa (Aiton) Hassk. Fruits in Downregulation of Mast Cells-Mediated Allergic Responses

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Thanh Sang Vo ◽  
Young-Sang Kim ◽  
Dai-Nghiep Ngo ◽  
Dai-Hung Ngo
Keyword(s):  
Mast Cells ◽  
Biological Activities ◽  
Interleukin 1 ◽  
Reactive Oxygen Species Generation ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Flowering Plant ◽  
Ionophore A23187 ◽  
Dependent Manner ◽  
Rhodomyrtus Tomentosa

Rhodomyrtus tomentosa, a flowering plant of Myrtaceae family from southern and southeastern Asia, was known to possess a rich source of structurally diverse and various biological activities. In this study, the inhibitory effect of R. tomentosa fruit extract (RFE) on allergic responses in calcium ionophore A23187-activated RBL-2H3 mast cells was investigated. The result showed that RFE was able to inhibit mast cell degranulation via decreasing β-hexosaminidase release and intracellular Ca2+ elevation at the concentration of 400 μg/ml. Moreover, the suppressive effects of RFE on the production of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were evidenced. In addition, RFE effectively scavenged DPPH radical and suppressed the reactive oxygen species generation in a dose-dependent manner. Notably, the pretreatment of RFE caused the downregulation of tyrosine kinase Fyn phospholipid enzyme phospholipase Cγ (PLCγ), extracellular-signal-regulated kinase (ERK), and nuclear factor kappa B (NF-κB) phosphorylation. These results indicated that RFE could be a promising inhibitor of allergic responses and may be developed as bioactive ingredient for prevention or treatment of allergic diseases.

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