Platelet Aggregation Evoked In Vitro and In Vivo by Phosphatidic Acids and Lysoderivatives: Identity with Substances in Aged Serum (DAS)

1979 ◽  
Vol 42 (02) ◽  
pp. 631-640 ◽  
Author(s):  
K A Schumacher ◽  
H G Classen ◽  
M Späth
Keyword(s):  
Platelet Count ◽  
Platelet Aggregation ◽  
Guinea Pig ◽  
Pulmonary Vascular Resistance ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Active Components ◽  
Phosphatidic Acids

SummaryIn serum incubated at 36° C for 18-24 hours a factor (DAS) develops which on intravenous injection into cats evokes platelet aggregation followed by an increase in pulmonary vascular resistance (PVR). This change in PVR is mediated via the platelets since it significantly correlates with the preinjection platelet count. There is evidence that phosphatidic acids (PA) and lysophosphatidic acids (LPA) are the active components of DAS. Investigations performed on platelet-rich plasma from man, cat, pig, dog, rabbit, guinea pig, and rat demonstrate that only human and feline platelets exposed to PA or to LPA are aggregated. Feline platelets are more sensitive to either compound than are the platelets from men; however, human platelets exhibit two exceptional properties, a) the sensitivity rapidly declines with time, b) pretreatment with subthreshold concentrations of LPA or PA induces a specific tachyphylaxis.

In Vitro and In Vivo Pharmacological Profiles of the PAF Receptor Antagonist SRI 63-675

1987 ◽  
Vol 57 (02) ◽  
pp. 187-190 ◽  
Author(s):  
Dean A Handley ◽  
Ronald G Van Valen ◽  
Christine M Winslow ◽  
John C Tomesch ◽  
Robert N Saunders
Keyword(s):  
Platelet Aggregation ◽  
Guinea Pig ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Induced Hypotension ◽  
Common Receptor ◽  
Ic50 Values ◽  
Paf Receptor

SummaryWe have examined a recently developed PAF antagonist SRI 63-675 (dimethyl-tetrahydrofuran-methoxyphosphinyloxy-ethylquinolinium) for its ability to inhibit several major PAF-induced physiological responses. The compound was a potent inhibitor of PAF-induced platelet aggregation in platelet rich plasma obtained from humans, guinea pigs, and rabbits, with IC50 values of 3.43, 0.25, and 0.97 μM, respectively. SRI 63-675 did not inhibit ADP, collagen nor epinephrine-induced human platelet aggregation. The IC50 for inhibition of PAF receptor binding to human platelets was 0.37 μM. In the rat SRI 63-675 inhibited 0.1 μg kg-1 i.v. PAF-induced hypotension, with an ED50 of 32 μg kg-1 i.v. Using the same PAF challenge in the guinea pig, SRI 63-675 inhibited the hemoconcentration (ED50 = 17 μg kg-1 i.v.) and bronchoconstriction (ED50 = 24 μg kg-1 i.v.) responses. In the primate, the ED50 was 28 μg kg-1 i.v. against 3.5 μg kg-1 PAF-induced hemoconcentration. The ratio (1:6) in the primate of PAF used (6.3 nmol kg-1) to antagonist at the ED50 (40.7 nmol kg-1) indicates exceptional potency of SRI 63675 in this species. The inhibition by SRI 63-675 of the major PAF-induced effects in the rat, guinea pig and primate suggests a common receptor may be involved in the expression of these PAF responses.

Enhancement of ADP-induced Platelet Aggregation by Adrenaline in Vivo and Its Prevention

1973 ◽  
Vol 29 (02) ◽  
pp. 490-498 ◽  
Author(s):  
Hiroh Yamazaki ◽  
Itsuro Kobayashi ◽  
Tadahiro Sano ◽  
Takio Shimamoto
Keyword(s):  
Platelet Count ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
The Other ◽  
Endothelial Surface ◽  
Important Interaction ◽  
Blood Coagulability ◽  
The Difference

SummaryThe authors previously reported a transient decrease in adhesive platelet count and an enhancement of blood coagulability after administration of a small amount of adrenaline (0.1-1 µg per Kg, i. v.) in man and rabbit. In such circumstances, the sensitivity of platelets to aggregation induced by ADP was studied by an optical density method. Five minutes after i. v. injection of 1 µg per Kg of adrenaline in 10 rabbits, intensity of platelet aggregation increased to 115.1 ± 4.9% (mean ± S. E.) by 10∼5 molar, 121.8 ± 7.8% by 3 × 10-6 molar and 129.4 ± 12.8% of the value before the injection by 10”6 molar ADP. The difference was statistically significant (P<0.01-0.05). The above change was not observed in each group of rabbits injected with saline, 1 µg per Kg of 1-noradrenaline or 0.1 and 10 µg per Kg of adrenaline. Also, it was prevented by oral administration of 10 mg per Kg of phenoxybenzamine or propranolol or aspirin or pyridinolcarbamate 3 hours before the challenge. On the other hand, the enhancement of ADP-induced platelet aggregation was not observed in vitro, when 10-5 or 3 × 10-6 molar and 129.4 ± 12.8% of the value before 10∼6 molar ADP was added to citrated platelet rich plasma (CPRP) of rabbit after incubation at 37°C for 30 second with 0.01, 0.1, 1, 10 or 100 µg per ml of adrenaline or noradrenaline. These results suggest an important interaction between endothelial surface and platelets in connection with the enhancement of ADP-induced platelet aggregation by adrenaline in vivo.

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.

The pharmacology of L-670,596, a potent and selective thromboxane/prostaglandin endoperoxide receptor antagonist

1989 ◽  
Vol 67 (9) ◽  
pp. 989-993 ◽  
Author(s):  
A. W. Ford-Hutchinson ◽  
Y. Girard ◽  
A. Lord ◽  
T. R. Jones ◽  
M. Cirino ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Guinea Pig ◽  
Receptor Antagonist ◽  
Competitive Inhibition ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Prostaglandin Endoperoxide ◽  
Induced Aggregation

L-670,596 ((−)6,8-difluoro-9-p-methylsulfonyl benzyl-1,2,3,4-tetrahydrocarbazol-1-yl-acetic acid) has been shown to be a potent receptor antagonist as evidenced by the inhibition of the binding of 125I-labeled PTA-OH to human platelets (IC50, 5.5 × 10−9 M), inhibition of U-44069 induced aggregation of human platelet rich plasma (IC50, 1.1 × 10−7 M), and competitive inhibition of contractions of the guinea pig tracheal chain induced by U-44069 (pA2,9.0). The compound was also active in vivo as shown by inhibition of arachidonic acid and U-44069 induced bronchoconstriction in the guinea pig (ED50 values, 0.04 and 0.03 mg/kg i.v., respectively), U-44069 induced renal vasoconstriction in the pig (ED50, 0.02 mg/kg i.v.), and inhibition of ex vivo aggregation of rhesus monkey platelets to U-44069 (active 1–5 mg/kg p.o.). The selectivity of the compound was indicated by the failure to inhibit, first, ADP-induced human or primate platelet aggregation and, second, bronchoconstriction in the guinea pig in vivo and contraction of the guinea pig tracheal chain in vitro to a variety of agonists. It is concluded that L-670,596 is a potent, selective, orally active thromboxane A2/prostaglandin endoperoxide receptor antagonist.Key words: thromboxane A2, thromboxane antagonist, prostaglandin endoperoxides, platelet aggregation.

GSK3β Is a Negative Regulator of Platelet Function In Vitro and In Vivo.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 395-395
Author(s):  
Donna S. Woulfe ◽  
Shelley August ◽  
Dongjun Li
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Ferric Chloride ◽  
Arterial Thrombosis ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Negative Regulator ◽  
Response Curves

Abstract GSK3β is a ser-thr kinase that is itself phosphorylated on ser9 by the kinase Akt. Because Akt has recently been shown to regulate platelet aggregation and arterial thrombosis in mice, we sought to identify Akt substrates in platelets that may play important roles in platelet function. We show here that the Akt effector, GSK3β, is present in platelets and becomes phosphorylated after treatment of mouse or human platelets with ADP or thrombin receptor-activating peptides (TRAP). Agonist-dependent phosphorylation of GSK3β is reduced by pre-treatment of mouse or human platelets with the PI3K inhibitor LY294002 and is also reduced in platelets from Akt2−/−Akt1+/− mice relative to non-littermate controls, suggesting that agonist-induced GSK3β phosphorylation is partially PI3K- and Akt-dependent. To determine whether GSK3β plays a role in platelet function, aggregation and secretion of dense granule contents were evaluated in human platelets treated with the GSK3 inhibitors, LiCl or SB216763. The dose-response curves for agonist-induced platelet aggregation and secretion were left-shifted in the presence of either inhibitor compared to untreated control platelets, suggesting that GSK3 activity suppresses platelet aggregation. Comparative immunoblots suggest that GSK3β is more highly expressed in platelets than GSK3α. Therefore, to confirm that GSKβ plays a suppressive role in platelet function, the aggregation of platelet-rich plasma (PRP) from GSK3β+/− mice was compared to that of non-littermate controls (GSK3β −/− mice die in utero). PRP from GSK3β+/− mice showed enhanced aggregation and secretion in response to U46619 or TRAP compared to control PRP. TRAP-induced binding of AlexaFluor-fibrinogen to platelet surfaces was also enhanced in washed platelets from GSK3β+/− mice compared to control platelets. Finally, the effect of GSK3β on platelet function in vivo was evaluated using two thrombosis models: a ferric chloride injury model of arterial thrombosis and a collagen-induced model of disseminated thrombosis. In the arterial thrombosis model, all GSK3β+/− mice (n=5) formed stable occlusive thrombi after ferric chloride injury to the carotid artery, whereas the majority of wildtype mice (67%) formed no thrombi, 27% formed stable occlusive thrombi, and 7% formed unstable thrombi under the same conditions (n=15). In a model of disseminated thrombosis, injection of a combination of collagen (170 μg/kg) and epinephrine (350 μM/kg) resulted in reduced survival of GSK3β+/− mice 10 minutes post-injection relative to wildtype mice (20%, n=5 versus 83%, n=6, respectively). Histological examination of lung sections suggested that all mice that died did so due to pulmonary embolism. These data suggest that removal of a single allele of GSK3β in mice confers enhanced sensitivity to thrombotic insult. Taken together, these results suggest that GSK3β is a substrate of Akt-dependent phosphorylation in platelets and, in contrast to the function of Akt, acts as a negative regulator of platelet function in vitro and in vivo.

The Effects of Brinolase (Fibrinolytic Enzyme from Aspergillus Oryzae) on Platelet Aggregation of Dog and Man

1972 ◽  
Vol 28 (01) ◽  
pp. 031-048 ◽  
Author(s):  
W. H. E Roschlau ◽  
R Gage
Keyword(s):  
Platelet Aggregation ◽  
Aspergillus Oryzae ◽  
Degradation Products ◽  
Blood Platelet ◽  
Human Platelets ◽  
Fibrinolytic Enzyme ◽  
Inhibitory Effects ◽  
Blood Platelet Aggregation

SummaryInhibition of blood platelet aggregation by brinolase (fibrinolytic enzyme from Aspergillus oryzae) has been demonstrated with human platelets in vitro and with dog platelets in vivo and in vitro, using both ADP and collagen as aggregating stimuli. It is suggested that the optimal inhibitory effects of brinolase occur indirectly through the generation of plasma fibrinogen degradation products, without compromising platelet viability, rather than by direct proteolysis of platelet structures.

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.

The Effect of Barbituric Acid Derivatives on Platelet Function in Vitro and in Vivo

1973 ◽  
Vol 30 (02) ◽  
pp. 315-326
Author(s):  
J. Heinz Joist ◽  
Jean-Pierre Cazenave ◽  
J. Fraser Mustard
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Barbituric Acid ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Primary Response ◽  
Sodium Pentobarbital ◽  
Barbituric Acid Derivatives

SummarySodium pentobarbital (SPB) and three other barbituric acid derivatives were found to inhibit platelet function in vitro. SPB had no effect on the primary response to ADP of platelets in platelet-rich plasma (PRP) or washed platelets but inhibited secondary aggregation induced by ADP in human PRP. The drug inhibited both phases of aggregation induced by epinephrine. SPB suppressed aggregation and the release reaction induced by collagen or low concentrations of thrombin, and platelet adherence to collagen-coated glass tubes. The inhibition by SPB of platelet aggregation was readily reversible and isotopically labeled SPB did not become firmly bound to platelets. No inhibitory effect on platelet aggregation induced by ADP, collagen, or thrombin could be detected in PRP obtained from rabbits after induction of SPB-anesthesia.

The Effect of Warfarin Sodium on the Duration of Platelet Aggregation

1967 ◽  
Vol 18 (03/04) ◽  
pp. 766-778 ◽  
Author(s):  
H. J Knieriem ◽  
A. B Chandler
Keyword(s):  
Platelet Count ◽  
Placebo Group ◽  
Platelet Aggregation ◽  
Prothrombin Time ◽  
Platelet Rich Plasma ◽  
Healthy Adults ◽  
Double Blind Study ◽  
Double Blind ◽  
Warfarin Sodium

SummaryThe effect of the administration of warfarin sodium (Coumadin®) on the duration of platelet aggregation in vitro was studied. Coumadin was given for 4 consecutive days to 10 healthy adults who were followed over a period of 9 days. The duration of adenosine diphosphate-induced platelet aggregation in platelet-rich plasma, the prothrombin time, and the platelet count of platelet-rich plasma were measured. Four other healthy adults received placebos and participated in a double-blind study with those receiving Coumadin.Although administration of Coumadin caused a prolongation of the prothrombin time to 2 or 21/2 times the normal value, a decrease in the duration of platelet aggregation was not observed. In most individuals who received Coumadin an increase in the duration of platelet aggregation occurred. The effect of Coumadin on platelet aggregation was not consistently related to the prothrombin time or to the platelet count. In the placebo group there was a distinct relation between the duration of platelet aggregation and the platelet count in platelet-rich plasma.The mean increase in the duration of platelet aggregation when compared to the control value before medication with Coumadin was 37.7%. In the placebo group there was a mean increase of 8.4%. The difference between the two groups is significant (p <0.001). Increased duration of platelet aggregation also occurred in two individuals who received Coumadin over a period of 10 and 16 days respectively.

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.

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