Endotoxin-Induced Platelet Activation in Human Whole Blood In Vitro

1988 ◽  
Vol 59 (03) ◽  
pp. 378-382 ◽  
Author(s):  
Gyorgy Csako ◽  
Eva A Suba ◽  
Ronald J Elin
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Atp Release ◽  
Human Platelets ◽  
Lag Phase ◽  
Human Whole Blood ◽  
Dose Dependent

SummaryThe effect of purified bacterial endotoxin was studied on human platelets in vitro. In adding up to 1 μg/mL of a highly purified endotoxin, we found neither aggregation nor ATP release in heparinized or citrated human platelet-rich plasma. On the other hand, endotoxin at concentrations as low as a few ng/mL (as may be found in septic patients) caused platelet aggregation in both heparinized and citrated human whole blood, as monitored by change in impedance, free platelet count, and size. Unlike collagen, the platelet aggregation with endotoxin occurred after a long lag phase, developed slowly, and was rarely coupled with measurable release of ATP. The platelet aggregating effect of endotoxin was dose-dependent and modified by exposure of the endotoxin to ionizing radiation. Thus, the activation of human platelets by “solubilized” endotoxin in plasma requires the presence of other blood cells. We propose that the platelet effect is mediated by monocytes and/or neutrophils stimulated by endotoxin.

Studies on in vitro effect of picotamide on human platelet aggregation in platelet-rich plasma and whole blood

1995 ◽  
Vol 77 (5) ◽  
pp. 399-410 ◽  
Author(s):  
Giovanni Anfossi ◽  
Simona Parisi ◽  
Isabella Russo ◽  
Elena M. Mularoni ◽  
Paola Massucco ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Human Platelet Aggregation ◽  
Vitro Effect

scholarly journals Effects of acetyl glyceryl ether phosphorylcholine on human platelet function in vitro

Blood ◽  
1981 ◽  
Vol 58 (5) ◽  
pp. 1027-1031 ◽  
Author(s):  
AJ Marcus ◽  
LB Safier ◽  
HL Ullman ◽  
KT Wong ◽  
MJ Broekman ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Initial Phase ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Strong Stimulus ◽  
Adp Release ◽  
Irreversible Aggregation ◽  
Induced Aggregation

Abstract AGEPC (PAF), at 1.9 x 10(-8) M or higher, induced concentration- dependent aggregation and release in human platelet-rich plasma. Comparative studies with arachidonate, collagen, ionophore, and ADP suggested that AGEPC was a strong stimulus for platelet aggregation and probably a moderate agonist for release, as well as a relatively weak inducer of TXA2 production. The initial phase of AGEPC-induced aggregation was independent of ADP release and TXA2 formation, since it was not inhibited by ASA, apyrase, or CP/CPK. Whereas irreversible aggregation always required ADP release, TXA2 formation was not essential in each instance. Thus, in several experiments, full aggregation responses took place in AGEPC-stimulated platelets that had been pretreated with ASA. AGEPC-induced release of 5-HT, beta - thromboglobulin and PF-4 occurred in parallel and were inhibited by both apyrase and ASA. Washed human platelets did not respond to exogenous AGEPC in the absence of ADP and did not appear to generate significant quantities of AGEPC upon stimulation with thrombin or ionophore.

R 68 070: Thromboxane A2 Synthetase Inhibition and Thromboxane A2/Prostaglandin Endoperoxide Receptor Blockade Combined in One Molecule - I. Biochemical Profile In Vitro

1989 ◽  
Vol 61 (01) ◽  
pp. 035-042 ◽  
Author(s):  
F De Clerck ◽  
J Beetens ◽  
D de Chaffoy de Courcelles ◽  
E Freyne ◽  
P A J Janssen
Keyword(s):  
Arachidonic Acid ◽  
Whole Blood ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Thromboxane A2 ◽  
Human Platelets ◽  
Receptor Blockade ◽  
Biochemical Profile ◽  
Prostaglandin Endoperoxide

SummaryR 68 070 or (E)-5-[[[(3-pyridinyl)[3-(trifluoromethyl)phenyl]- methylen]amino]oxy] pentanoic acid (Janssen Research Foundation, Belgium) combines specific thromboxane A2 (TXA2) synthetase inhibition with TXA2/prostaglandin endoperoxide receptor blockade in one molecule.In vitro, the compound specifically inhibits the production of TXB2 from [14C] arachidonic acid by washed human platelets (IC50 = 8.2 × 10-9 M) and by platelet microsomes (IC50 = 3.6 × 10-9 M), of MDA (IC50 = 1.91 × 10-8 M) and of TXB2 (IC50 = 1.47 × 10-8 M) by thrombin-coagulated human platelet-rich plasma (P.R.P.) and whole blood respectively and increases the levels of PGD2, PGE2, PGF2α and 6-keto-PGF1α. The activity of cyclo-oxygenase-, prostacyclin synthetase-, 5-, 12- and 15-lipoxygenase-enzymes are not affected. Additionally, R 68 070 inhibits human platelet aggregation in P.R.P. induced by U 46619 3 × 10-7 M to 2 × 10-6 M (IC50 = 2.08 × 10-6 M to 2.66 × 10-5 M), collagen 0.5 to 2 μg/ml (IC50 = 2.85 × 10-6 M to 4.81 × 10-5 M), arachidonic acid 7.5 × 10-4 M to 2 × 10- M (IC50 = 2.1 × 10-8 M to 3.3 × 10-8 M) and the U 46619 (1 × 10-7 M)-induced accumulation of [32P] phosphatidic acid (IC50 = 5.24 × 10-7 M) in washed human platelets. Collagen (0.75 μg/ml)-induced ATP release (IC50 = 4.1 × 10-6 M), ADP (1 to 2.5 × 10-6 M)-induced second wave aggregation (IC50 = 3.19 × 10-6 M) in P.R.P. as well as the collagen (1 μg/ml)-induced adhesion/aggregation reaction in human whole blood (IC50 = 1.02 × 10-5 M) are reduced as well by the compoun.Primary platelet reactions induced by serotonin, ADP, PAF, or A 23187, platelet adenylate cyclase- and cAMP phosphodiesterase-activity, and platelet inhibitory activities of PGD2, PGI2, PGE2, PGE1 are not modified by R 68 070.This biochemical profile is compatible with a dual mechanism of action of R 68 070, namely TXA2 synthetase inhibition at low concentrations, plus additionally TXA2/prostaglandin endoperoxide receptor blockade at higher concentrations

Diurnal variation in melatonin effect on adenosine triphosphate and serotonin release by human platelets

1990 ◽  
Vol 123 (4) ◽  
pp. 453-458 ◽  
Author(s):  
María de las M. Del Zar ◽  
Marta Martinuzzo ◽  
Daniel P. Cardinali ◽  
Luis O. Carreras ◽  
María I. Vacas
Keyword(s):  
Platelet Aggregation ◽  
Diurnal Variation ◽  
Adenosine Triphosphate ◽  
Platelet Rich Plasma ◽  
Atp Release ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Serotonin Release ◽  
Normal Volunteers ◽  
Dose Dependent

Abstract. The effect of the pineal hormone melatonin on adenosine diphosphate-induced human platelet aggregation and adenosine triphosphate release was assessed in platelet-rich plasma obtained from normal volunteers at 08.30 and 20.30 h. In 10−7-10−5 mol/l concentrations melatonin inhibited ADP-induced platelet aggregation only in the evening (p<0.05). ADP-induced ATP release, an index of platelet secretory processes, showed a generally greater, dose-dependent inhibition after adding melatonin (10−9-10−5 mol/l) at 20.30 h as compared with 08.30 h. The inhibitory activity of melatonin (10−9-10−5 mol/l) on [3H]serotonin release elicited by thrombin in washed human platelets obtained from normal volunteers was dose-dependent; the effect was generally greater at 20.30 h. The activity of the potent platelet anti-aggregating agent prostacyclin did not exhibit diurnal differences with respect to impairing ADP-induced platelet-rich plasma aggregation. These results indicate the existence of a diurnal variation of sensitivity to melatonin in human platelets.

scholarly journals Effects of acetyl glyceryl ether phosphorylcholine on human platelet function in vitro

Blood ◽  
1981 ◽  
Vol 58 (5) ◽  
pp. 1027-1031
Author(s):  
AJ Marcus ◽  
LB Safier ◽  
HL Ullman ◽  
KT Wong ◽  
MJ Broekman ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Initial Phase ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Strong Stimulus ◽  
Adp Release ◽  
Irreversible Aggregation ◽  
Induced Aggregation

AGEPC (PAF), at 1.9 x 10(-8) M or higher, induced concentration- dependent aggregation and release in human platelet-rich plasma. Comparative studies with arachidonate, collagen, ionophore, and ADP suggested that AGEPC was a strong stimulus for platelet aggregation and probably a moderate agonist for release, as well as a relatively weak inducer of TXA2 production. The initial phase of AGEPC-induced aggregation was independent of ADP release and TXA2 formation, since it was not inhibited by ASA, apyrase, or CP/CPK. Whereas irreversible aggregation always required ADP release, TXA2 formation was not essential in each instance. Thus, in several experiments, full aggregation responses took place in AGEPC-stimulated platelets that had been pretreated with ASA. AGEPC-induced release of 5-HT, beta - thromboglobulin and PF-4 occurred in parallel and were inhibited by both apyrase and ASA. Washed human platelets did not respond to exogenous AGEPC in the absence of ADP and did not appear to generate significant quantities of AGEPC upon stimulation with thrombin or ionophore.

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.

Interactions of Staphylokinase with Human Platelets

1995 ◽  
Vol 73 (03) ◽  
pp. 472-477 ◽  
Author(s):  
H R Lijnen ◽  
B Van Hoef ◽  
D Collen
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Specific Binding ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Normal Plasma ◽  
Atp Secretion ◽  
Platelet Disaggregation ◽  
Activation Rate

SummaryThe interactions of recombinant staphylokinase (SakSTAR) with human platelets were investigated in a buffer milieu, in a human plasma milieu in vitro, and in plasma from patients with acute myocardial infarction (AMI) treated with SakSTAR.In a buffer milieu, the activation rate of plasminogen by SakSTAR or streptokinase (SK) was not significantly altered by addition of platelets. Specific binding of SakSTAR or SK to either resting or thrombin- activated platelets was very low. ADP-induced or collagen-induced platelet aggregation in platelet-rich plasma (PRP) was 94 ± 2.7% or 101 ± 1.7% of control in the presence of 0.1 to 20 μM SakSTAR, with corresponding values of 95 ± 2.8% or 90 ± 4.6% of control in the presence of 0.1 to 4 μM SK. No effects were observed on platelet disaggregation. ATP secretion following collagen-induced platelet aggregation was 4.3 ± 0.26 μM for SakSTAR (at concentrations of 0.1 to 20 μM) and 4.4 ± 0.35 μM for SK (at concentrations of 0.1 to 4 μM), as compared to 3.4 ± 0.70 μM in the absence of plasminogen activator.Fifty % lysis in 2 h (C50) of 60 μl 125I-fibrin labeled platelet-poor plasma (PPP) clots prepared from normal plasma or from plasma of patients with Glanzmann thrombasthenia and immersed in 0.5 ml normal plasma, was obtained with 12 or 16 nM SakSTAR and with 49 or 40 nM SK, respectively. C50 values for lysis of 60 μl PRP clots prepared from normal or patient plasma were also comparable for SakSTAR (19 or 21 nM), whereas SK was 2-fold more potent toward PRP clots prepared from Glanzmann plasma as compared to normal plasma (C50 of 130 versus 270 nM).No significant effect of SakSTAR on platelet function was observed in plasma from patients with AMI treated with SakSTAR, as revealed by unaltered platelet count, platelet aggregation and ATP secretion.Thus, no effects of high SakSTAR concentrations were observed on human platelets in vitro, nor of therapeutic SakSTAR concentrations on platelet function in plasma.

Dipyridamole Inhibits Platelet Aggregation in Whole Blood

1983 ◽  
Vol 50 (04) ◽  
pp. 852-856 ◽  
Author(s):  
P Gresele ◽  
C Zoja ◽  
H Deckmyn ◽  
J Arnout ◽  
J Vermylen ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Significant Negative Correlation ◽  
Significant Inhibition ◽  
Oral Drug ◽  
Human Blood Samples ◽  
Induced Aggregation

SummaryDipyridamole possesses antithrombotic properties in the animal and in man but it does not inhibit platelet aggregation in plasma. We evaluated the effect of dipyridamole ex vivo and in vitro on platelet aggregation induced by collagen and adenosine- 5’-diphosphate (ADP) in human whole blood with an impedance aggregometer. Two hundred mg dipyridamole induced a significant inhibition of both ADP- and collagen-induced aggregation in human blood samples taken 2 hr after oral drug intake. Administration of the drug for four days, 400 mg/day, further increased the antiplatelet effect. A significant negative correlation was found between collagen-induced platelet aggregation in whole blood and dipyridamole levels in plasma (p <0.001). A statistically significant inhibition of both collagen (p <0.0025) and ADP-induced (p <0.005) platelet aggregation was also obtained by incubating whole blood in vitro for 2 min at 37° C with dipyridamole (3.9 μM). No such effects were seen in platelet-rich plasma, even after enrichment with leukocytes. Low-dose adenosine enhanced in vitro inhibition in whole blood.Our results demonstrate that dipyridamole impedes platelet aggregation in whole blood by an interaction with red blood cells, probably involving adenosine.

Arginine vasopressin release from human platelets after irreversible aggregation

1990 ◽  
Vol 78 (1) ◽  
pp. 113-116 ◽  
Author(s):  
Giovanni Anfossi ◽  
Elena Mularoni ◽  
Mariella Trovati ◽  
Paola Massucco ◽  
Luigi Mattiello ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Arginine Vasopressin ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Vasopressin Release ◽  
Irreversible Aggregation ◽  
Local Release

1. The release of arginine vasopressin from human platelets was investigated in platelet-rich plasma after irreversible aggregation induced by adenosine 5′-pyrophosphate, collagen, sodium arachidonate, thrombin and adrenaline in vitro. 2. Arginine vasopressin levels were significantly higher in the supernatant from stimulated platelet-rich plasma than from unstimulated samples, reaching 3.5 × 10−12 (range 1.6–12.5 × 10−12) mol/l in the absence of an aggregating agent, 8.8 × 10−12 (range 4.2–17.5 × 10−12) mol/l after adenosine 5′-pyrophosphate, 13.7 × 10−12 (2.2–63.2 × 10−12) mol/l after collagen, 7.8 × 10−12 (2.2–14.6 × 10−12) mol/l after sodium arachidonate, 7.8 × 10−12 (2.2–16.3 × 10−12) mol/l after thrombin and 12.2 × 10−12 (4.8–32.1 × 10−12) mol/l after adrenaline. 3. An arginine vasopressin level of 18 × 10−12 mol/l, which can be achieved physiologically, increased the sensitivity of platelets to adenosine 5′-pyrophosphate and collagen in vitro; the same concentration of arginine vasopressin caused a potentiation of the effect of catecholamines on the response of platelets to sodium arachidonate. 4. These results indicate that intraplatelet arginine vasopressin is released during aggregation and suggest that a local release of arginine vasopressin could occur after complete platelet aggregation in vivo.

Sign in / Sign up

Export Citation Format

Share Document