scholarly journals Impaired platelet response to thromboxane-A2 and defective calcium mobilization in a patient with a bleeding disorder

Blood ◽  
1981 ◽  
Vol 57 (3) ◽  
pp. 545-552 ◽  
Author(s):  
B Lages ◽  
C Malmsten ◽  
HJ Weiss ◽  
B Samuelsson
Keyword(s):  
Platelet Rich Plasma ◽  
Calcium Ionophore ◽  
Thromboxane A2 ◽  
Adenosine Diphosphate ◽  
Bleeding Disorder ◽  
Ionophore A23187 ◽  
Platelet Response ◽  
Thromboxane Synthetase ◽  
Defect Aggregation ◽  
Induced Aggregation

Abstract Platelet aggregation, secretion, and thromboxane formation induced by various agonists, including arachidonate, prostaglandin-G2 (PGG2), and thromboxane-A2 (TxA2), were examined in a patient with a bleeding disorder who was previously reported to have a TxA2-related defect. Aggregation and 14C-5HT secretion were decreased, and no TxB2 formation occurred in response to adenosine diphosphate (ADP), epinephrine, or collagen. Arachidonate-induced aggregation and TxB2 formation, and PGG2- induced aggregation (but not TxB2 formation) were impaired at low agonist concentrations. The patient's platelets did not aggregate in response to TxA2 generated from arachidonate in normal platelets, but were capable of synthesizing TxA2 from both arachidonate and PGG2. In addition, aggregation and secretion induced by low concentrations of the ionophore A23187 were impaired in platelet-rich plasma (PRP) and in gel-filtered platelets in the absence of extracellular calcium; these responses became normal at higher A23187 concentrations or, in GFP, at low A23187 concentrations in the presence of exogenous calcium. These findings indicate that the TxA2 defect in this patient does not result from a thromboxane synthetase deficiency, but may be due to impaired mobilization of platelet calcium, and thus are consistent with the possibility that TxA2 may act as a calcium ionophore.

scholarly journals Impaired platelet response to thromboxane-A2 and defective calcium mobilization in a patient with a bleeding disorder

Blood ◽  
1981 ◽  
Vol 57 (3) ◽  
pp. 545-552 ◽  
Author(s):  
B Lages ◽  
C Malmsten ◽  
HJ Weiss ◽  
B Samuelsson
Keyword(s):  
Platelet Rich Plasma ◽  
Calcium Ionophore ◽  
Thromboxane A2 ◽  
Adenosine Diphosphate ◽  
Bleeding Disorder ◽  
Ionophore A23187 ◽  
Platelet Response ◽  
Thromboxane Synthetase ◽  
Defect Aggregation ◽  
Induced Aggregation

Platelet aggregation, secretion, and thromboxane formation induced by various agonists, including arachidonate, prostaglandin-G2 (PGG2), and thromboxane-A2 (TxA2), were examined in a patient with a bleeding disorder who was previously reported to have a TxA2-related defect. Aggregation and 14C-5HT secretion were decreased, and no TxB2 formation occurred in response to adenosine diphosphate (ADP), epinephrine, or collagen. Arachidonate-induced aggregation and TxB2 formation, and PGG2- induced aggregation (but not TxB2 formation) were impaired at low agonist concentrations. The patient's platelets did not aggregate in response to TxA2 generated from arachidonate in normal platelets, but were capable of synthesizing TxA2 from both arachidonate and PGG2. In addition, aggregation and secretion induced by low concentrations of the ionophore A23187 were impaired in platelet-rich plasma (PRP) and in gel-filtered platelets in the absence of extracellular calcium; these responses became normal at higher A23187 concentrations or, in GFP, at low A23187 concentrations in the presence of exogenous calcium. These findings indicate that the TxA2 defect in this patient does not result from a thromboxane synthetase deficiency, but may be due to impaired mobilization of platelet calcium, and thus are consistent with the possibility that TxA2 may act as a calcium ionophore.

Effects of Etamsylate on Platelet Functions and Arachidonic Acid Metabolism

1982 ◽  
Vol 48 (03) ◽  
pp. 330-333 ◽  
Author(s):  
M Okuma ◽  
H Takayama ◽  
T Sugiyama ◽  
S Sensaki ◽  
H Uchino
Keyword(s):  
Platelet Aggregation ◽  
Atp Release ◽  
Calcium Ionophore ◽  
Thromboxane A2 ◽  
Arachidonic Acid Metabolism ◽  
Ionophore A23187 ◽  
Platelet Response ◽  
Human Platelet Aggregation ◽  
Induced Aggregation ◽  
Platelet Functions

SummaryThe effects of etamsylate on human platelet aggregation and ATP release as well as on the arachidonate metabolism by the platelet have been studied. Etamsylate enhanced these platelet functions induced by arachidonic add (AA), thromboxane A2, collagen and caldum ionophore A23187 but not those induced by ADP and epinephrine. In experiments with cyclooxygenase-inhibited platelets, AA-induced platelet aggregation was completely inhibited and it was not enhanced by etamsylate, while A23187-induced aggregation was partially inhibited and this aggregation was enhanced by etamsylate. Platelet AA metabolism including thrombin-induced AA liberation from phospholipids as well as the lipoxygenase and cyclo-oxygenase pathways was not significantly affected by etamsylate. These results suggested that etamsylate enhanced platelet response to thromboxane A2 and calcium ionophore and that this could be included as a mechanism for its potentiating effect on platelet functions.

Congenital Deficiency Of Cyclo-Oxygenase In A Woman With Generalized Arteriosclerosis

1981 ◽  
Author(s):  
Z Boda ◽  
E Tamás ◽  
L Altorjay ◽  
Gy Pflieger ◽  
K Rak
Keyword(s):  
Platelet Rich Plasma ◽  
Calcium Ionophore ◽  
Drug Effects ◽  
Vascular Diseases ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Special Importance ◽  
Bleeding Tendency ◽  
Congenital Deficiency ◽  
Induced Aggregation

A 52-year old woman with congenital cyclooxygenase deficiency who had moderate bleeding tendency and severe generalized arteriosclerosis is reported.Diagnosis based on the following data: secondary platelet aggregation induced by adrenaline, ADP, ristomycin, collagen, thrombin was absent; platelet completely failed to aggregate by arachidonic acid while aggregation induced by calcium ionophore A23187 was normal; no malondialdehyde formation could be detected in the platelet rich plasma /PRP/ in four different times /for exclu- sing any drug effects/. The abnormal adrenaline and ADP induced aggregation were not corrected when patient’s PRP was mixed in equal proportions with that of a normal subject ingesting aspirin.Although our patient had been free from severe thrombotic episodes, expressed signs of generalized arteriosclerosis could be detected.Until now only five cases of congenital deficiency of cyclo-oxygenase have been described /Malmsten et al., Weiss and Lages, Lagarde et al., Pareti et al./. However, in these patients no signs of arterial vascular diseases were mentioned.The special importance of this new case comes from the fact that life-long deficiency of cyclooxygenase enzyme could not protect from progressive vascular disease which might prove again that chronic intake of large doses of aspirin cannot prevent arterial disorder.

INHIBITION OF HUMAN PLATELET FUNCTION BY PCA-4230

1987 ◽  
Author(s):  
M P Ortega ◽  
C Sunkel ◽  
J G Priego
Keyword(s):  
Platelet Function ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Platelet Activating Factor ◽  
Atp Release ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Synthetic Compound ◽  
Induced Aggregation

PCA-4230 (3-{2-(N-l,2-benzisothiazolyl-3(2H)one-1,1-dioxide) ethoxycarbonyl}-2,6-dimethyl-5-ethoxycarbonyl-4-methyl-l,4-dihy-dropyridine) is a new synthetic compound which has been selected after evaluation of .several series of molecules included in an ex tensive program of synthesis and biological screening.The purpose of this study was to investigate the In vUjiO effects of PCA-4230 on human platelet function.Platelet aggregation (PA) was measured, in platelet rich plasma (PRP) or washed platelets, according to Born’s technique. Release reaction (RR) was measured by the luminiscence method as adenosine triphosphate (ATP) release in response to stimulation. Aggregating agents were adenosine diphosphate (ADP), epinephrine (Epi), collagen (Col), thrombin (Thr), calcium ionophore (A23187) arachidonic acid (AA), thromboxane agonist (U46619) or platelet activating factor (PAF). Incubation with PCA-4230 (1 to 10 μM) we re carried out at 37°C for 15 minutes. PCA-4230 potentiation of Prostacyclin (PGI2) anti-aggregatory activity was also studied by addition to PRP of PGI2, PCA-4230 or both, and PA by ADP.PCA-4230 inhibited PA and RR in PRP in a concentration-dependent fashion when Col, Epi, U46619 or PAF were used as agonists. AA-and Thr-induced aggregation were only slightly impaired and no in hibition was shown on ADP or A23187-triggered activation. A23187-induced aggregation and RR were inhibited only in the absence of extracellular Ca++ in washed platelets. This effect was overcome by addition of Ca++ 1 mM. Additionally, the inhibitory effect of PGI2 on ADP-induced PA, was synergistically potentiated by PCA-4230, suggesting inhibitory activity of the compound on cjy clic nucleotide phosphodiesterase.Since PCA-4230 inhibited PA and RR induced by Epi, U46619 and PAF, mediated viareceptor-agonist binding, and Col-inducedactivation, it is reasonable to suspect that common process(es) may be involved. Recently, it has been suggested that intraplatelet Ca++ levels, actingas a second messenger, are directly linked to the d<2 gree of platelet activation.Therefore, the ability of PCA-4230 to modulate platelet function appears, at leastin part, to be due to regulation of cytosolic Ca++ levels. This hypothesis is confii: med by the results with A23187-induced aggregation in absence of extracellular Ca++.

The Relationship between the Production of Thromboxane B2 and Malondialdehyde by Human Blood Platelets

1980 ◽  
Vol 59 (2) ◽  
pp. 131-135 ◽  
Author(s):  
L. C. Best ◽  
P. B. B. Jones ◽  
R. G. G. Russell
Keyword(s):  
Platelet Rich Plasma ◽  
Blood Platelets ◽  
Thromboxane B2 ◽  
Ionophore A23187 ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Thromboxane Synthetase ◽  
Malondialdehyde Formation ◽  
Induced Aggregation ◽  
The Relationship

1. The formation of thromboxane B2 and malondialdehyde was studied in human platelet-rich plasma, in gel-filtered platelets and in bovine platelet microsomes. 2. Exogenous sodium arachidonate was converted into thromboxane B2 and malondialdehyde in a concentration-dependent manner. Pre-incubation of platelets with aspirin inhibited the production of both thromboxane B2 and malondialdehyde, although malondialdehyde could apparently be detected in the absence of thromboxane B2. 3. The aggregating agents, thrombin, collagen and the ionophore A23187 also caused production of thromboxane B2 and malondialdehyde. ADP and adrenaline produced a smaller rise whilst the endoperoxide analogue U 46619 had only a slight influence on thromboxane and malondialdehyde, even though they all induced aggregation. 4. Pre-incubation of platelets with imidazole or 1-N-butylimidazole, which inhibit thromboxane synthetase, resulted in an inhibition of both thromboxane B2 and malondialdehyde formation in response to collagen. 5. The results indicate that thromboxane B2 and malondialdehyde are formed in parallel, in comparable quantities. However, under the conditions used in these studies, the apparent amounts of malondialdehyde exceed those of thromboxane B2, especially in the presence of exogenous arachidonate. Thus the thiobarbiturate reaction used to assay malondialdehyde may detect other products of lipid peroxidation. 6. Platelet thromboxane B2 concentrations did not always relate to the extent of aggregation. In particular, platelet aggregation could occur in the absence of detectable thromboxane B2 production.

Testosterone Potentiation of Ionophore and ADP Induced Platelet Aggregation : Relationship to Arachidonic Acid Metabolism

1981 ◽  
Vol 46 (02) ◽  
pp. 538-542 ◽  
Author(s):  
R Pilo ◽  
D Aharony ◽  
A Raz
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Unsaturated Fatty Acids ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Arachidonic Acid Metabolism ◽  
Ionophore A23187 ◽  
Low Concentrations ◽  
Induced Aggregation

SummaryThe role of arachidonic acid oxygenated products in human platelet aggregation induced by the ionophore A23187 was investigated. The ionophore produced an increased release of both saturated and unsaturated fatty acids and a concomitant increased formation of TxA2 and other arachidonate products. TxA2 (and possibly other cyclo oxygenase products) appears to have a significant role in ionophore-induced aggregation only when low concentrations (<1 μM) of the ionophore are employed.Testosterone added to rat or human platelet-rich plasma (PRP) was shown previously to potentiate platelet aggregation induced by ADP, adrenaline, collagen and arachidonic acid (1, 2). We show that testosterone also potentiates ionophore induced aggregation in washed platelets and in PRP. This potentiation was dose and time dependent and resulted from increased lipolysis and concomitant generation of TxA2 and other prostaglandin products. The testosterone potentiating effect was abolished by preincubation of the platelets with indomethacin.

scholarly journals Synergistic inhibition of platelet activation by plasmin and prostaglandin I2

Blood ◽  
1987 ◽  
Vol 69 (5) ◽  
pp. 1504-1507
Author(s):  
AI Schafer ◽  
GB Zavoico ◽  
J Loscalzo ◽  
AK Maas
Keyword(s):  
Cyclic Amp ◽  
Platelet Activation ◽  
Platelet Rich Plasma ◽  
Thromboxane A2 ◽  
Prostaglandin I2 ◽  
Synergistic Inhibition ◽  
Tissue Plasminogen ◽  
A Site ◽  
Induced Aggregation ◽  
Inhibition Of Thrombin

Endothelial cell prostacyclin (PGI2) inhibits platelet activation by raising platelet cyclic AMP. Previously, platelet activation was also shown to be blocked by plasmin formed by endothelium-derived tissue plasminogen activator (TPA). We have now studied interactions between PGI2 and plasmin in the control of platelet function. PGI2 and plasmin cause synergistic inhibition of thrombin- and ADP-induced aggregation of washed platelets. Inhibition by PGI2 is similarly potentiated by TPA added to platelet-rich plasma to generate plasmin. Thrombin-stimulated rise in platelet cytosolic Ca2+, measured by fura2 fluorescence, and thromboxane A2 formation, measured by radioimmunoassay (RIA), are likewise synergistically inhibited by PGI2 and plasmin. Plasmin neither increases nor potentiates PGI2-stimulated increases in platelet cyclic AMP. Thus, PGI2 and plasmin cause synergistic inhibition of platelet activation by both cyclic AMP-dependent and independent mechanisms. This interaction between two different endothelium-derived products may play an important role in localizing the hemostatic plug to a site of vascular injury by preventing further thrombin-mediated accrual of platelets.

Aspirin-Dependent Effects on Purinergic P2Y1 Receptor Expression

2019 ◽  
Vol 119 (05) ◽  
pp. 726-734 ◽  
Author(s):  
Isabella Massimi ◽  
Laura Alemanno ◽  
Maria Guarino ◽  
Raffaella Guerriero ◽  
Massimo Mancone ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Thromboxane A2 ◽  
Adenosine Diphosphate ◽  
Receptor Expression ◽  
P2y1 Receptor ◽  
Biochemical Pathway ◽  
Thromboxane A2 Receptor ◽  
Induced Aggregation

AbstractChronic treatment with aspirin in healthy volunteers (HVs) is associated with recovery of adenosine diphosphate (ADP)-induced platelet activation. The purinergic P2Y1 receptor exerts its effects via a Gq-protein, which is the same biochemical pathway activated by thromboxane-A2 receptor. We hypothesized that recovery of ADP-induced platelet activation could be attributed to increased P2Y1 expression induced by chronic aspirin exposure. We performed a multi-phase investigation which embraced both in vitro and in vivo experiments conducted in (1) human megakaryoblastic DAMI cells, (2) human megakaryocytic progenitor cell cultures, (3) platelets obtained from HVs treated with aspirin and (4) platelets obtained from aspirin-treated patients. DAMI cells treated with aspirin or WY14643 (PPARα agonist) had a significant up-regulation of P2Y1 mRNA, which was shown to be a PPARα-dependent process. In human megakaryocytic progenitors, in the presence of aspirin or WY14643, P2Y1 mRNA expression was higher than in mock culture. P2Y1 expression increased in platelets obtained from HVs treated with aspirin for 8 weeks. Platelets obtained from patients who were on aspirin for more than 2 months had increased P2Y1 expression and ADP-induced aggregation compared with patients on aspirin treatment for less than a month. Overall, our results suggest that aspirin induces genomic changes in megakaryocytes leading to P2Y1 up-regulation and that PPARα is the nuclear receptor involved in this regulation. Since P2Y1 is coupled to the same Gq-protein of thromboxane-A2 receptor, platelet adaptation in response to pharmacological inhibition seems not to be receptor specific, but may involve other receptors with the same biochemical pathway.

scholarly journals Molecular characterization of familial bleeding disorder with impaired platelet response to thromboxane A2.

1994 ◽  
Vol 64 ◽  
pp. 169
Author(s):  
Takako Hirata ◽  
Akira Kakizuka ◽  
Fumitaka Ushikubi ◽  
Minoru Okuma ◽  
Shuh Narumiya
Keyword(s):  
Molecular Characterization ◽  
Thromboxane A2 ◽  
Bleeding Disorder ◽  
Platelet Response

scholarly journals Spectrophotometric Determination of the Aggregation Activity of Platelets in Platelet-Rich Plasma for Better Quality Control

2019 ◽  
Vol 7 (2) ◽  
pp. 61 ◽  
Author(s):  
Tetsuhiro Tsujino ◽  
Kazushige Isobe ◽  
Hideo Kawabata ◽  
Hachidai Aizawa ◽  
Sadahiro Yamaguchi ◽  
...  
Keyword(s):  
Quality Control ◽  
Spectrophotometric Method ◽  
Platelet Rich Plasma ◽  
Antiplatelet Agent ◽  
Adenosine Diphosphate ◽  
Buffer Solution ◽  
Platelet Concentration ◽  
Aggregation Activity ◽  
Induced Aggregation

Although platelet-rich plasma (PRP) is now widely used in regenerative medicine and dentistry, contradictory clinical outcomes have often been obtained. To minimize such differences and to obtain high quality evidence from clinical studies, the PRP preparation protocol needs to be standardized. In addition, emphasis must be placed on quality control. Following our previous spectrophotometric method of platelet counting, in this study, another simple and convenient spectrophotometric method to determine platelet aggregation activity has been developed. Citrated blood samples were collected from healthy donors and used. After centrifugation twice, platelets were suspended in phosphate buffered saline (PBS) and adenosine diphosphate (ADP)-induced aggregation was determined using a spectrophotometer at 615 nm. For validation, platelets pretreated with aspirin, an antiplatelet agent, or hydrogen peroxide (H2O2), an oxidative stress-inducing agent, were also analyzed. Optimal platelet concentration, assay buffer solution, and representative time point for determination of aggregation were found to be 50–100 × 104/μL, PBS, and 3 min after stimulation, respectively. Suppressed or injured platelets showed a significantly lower aggregation response to ADP. Therefore, it suggests that this spectrophotometric method may be useful in quick chair-side evaluation of individual PRP quality.

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