Effects of Halothane on Platelet Function

SummaryHuman platelets in platelet rich plasma (PRP) incubated at 37° C with 0.3–2% halothane for 5–10 min lost the ability to aggregate with ADP, epinephrine and collagen.At the same time uptake and release of 14C-serotonin was inhibited. When halothane supply was removed, platelet functions rapidly returned to normal. However, after high concentrations of halothane, the inhibition of platelet aggregation was irreversible or only partially reversible.The results suggest that halothane anaesthesia produces a transient impairment of platelet function.

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Interactions of Staphylokinase with Human Platelets

Thrombosis and Haemostasis ◽

10.1055/s-0038-1653799 ◽

1995 ◽

Vol 73 (03) ◽

pp. 472-477 ◽

Cited By ~ 5

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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Activation of human platelets by immune complexes prepared with cationized human IgG

Blood ◽

10.1182/blood.v82.10.3045.bloodjournal82103045 ◽

1993 ◽

Vol 82 (10) ◽

pp. 3045-3051

Author(s):

M Schattner ◽

M Lazzari ◽

AS Trevani ◽

E Malchiodi ◽

AC Kempfer ◽

...

Keyword(s):

Platelet Aggregation ◽

Platelet Activation ◽

Immune Complexes ◽

Platelet Rich Plasma ◽

Human Platelets ◽

Human Igg ◽

Experimental Conditions ◽

Induce Platelet Aggregation ◽

Soluble Immune Complexes ◽

High Concentrations

The present study shows that the ability of soluble immune complexes (IC), prepared with human IgG and rabbit IgG antibodies against human IgG, to trigger platelet activation was markedly higher for IC prepared with cationized human IgG (catIC) compared with those prepared with untreated human IgG (cIC). CatIC induced platelet aggregation and adenosine triphosphate release in washed platelets (WP), gel-filtered platelets (GFP), or platelet-rich plasma (PRP) at physiologic concentrations of platelets (3 x 10(8)/mL) and at low concentrations of catIC (1 to 30 micrograms/mL). On the contrary, under similar experimental conditions, cIC did not induce aggregation in PRP, WP, or GFP. Low aggregation responses were only observed using high concentrations of both WP (9 x 10(8)/mL) and cIC (500 micrograms/mL). Interestingly, catIC were also able to induce platelet activation under nonaggregating conditions, as evidenced by P-selectin expression. Cationized human IgG alone did not induce platelet aggregation in PRP but triggered either WP or GFP aggregation. However, the concentration needed to induce these responses, was about eightfold higher than those required for catIC. The responses induced either by catIC or cationized human IgG were completely inhibited by treatment with heparin, dextran sulphate, EDTA, prostaglandin E1, or IV3, a monoclonal antibody against the receptor II for the Fc portion of IgG (Fc gamma RII). The data presented in this study suggest that IgG charge constitutes a critical property that conditions the ability of IC to trigger platelet activation.

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Enhanced platelet aggregation and activation under conditions of hypothermia

Thrombosis and Haemostasis ◽

10.1160/th07-03-0189 ◽

2007 ◽

Vol 98 (12) ◽

pp. 1266-1275 ◽

Cited By ~ 41

Author(s):

Ruben Xavier ◽

Ann White ◽

Susan Fox ◽

Robert Wilcox ◽

Stan Heptinstall

Keyword(s):

Cardiac Surgery ◽

Platelet Aggregation ◽

Platelet Function ◽

Whole Blood ◽

Platelet Rich Plasma ◽

Baseline Levels ◽

Spontaneous Aggregation ◽

High Concentrations ◽

Induced Aggregation ◽

P2y12 Antagonist

SummaryThe effects on platelet function of temperatures attained during hypothermia used in cardiac surgery are controversial. Here we have performed studies on platelet aggregation in whole blood and platelet-rich plasma after stimulation with a range of concentrations of ADP, TRAP, U46619 and PAF at both 28°C and 37°C. Spontaneous aggregation was also measured after addition of saline alone. In citrated blood, spontaneous aggregation was markedly enhanced at 28°C compared with 37°C. Aggregation induced by ADP was also enhanced. Similar results were obtained in hirudinised blood. There was no spontaneous aggregation in PRP but ADP-induced aggregation was enhanced at 28°C. The P2Y12 antagonist AR-C69931 inhibited all spontaneous aggregation at 28°C and reduced all ADP-induced aggregation responses to small, reversible responses. Aspirin had no effect. Aggregation was also enhanced at 28°C compared with 37°C with low but not high concentrations of TRAP and U46619. PAF-induced aggregation was maximal at all concentrations when measured at 28°C, but reversal of aggregation was seen at 37°C. Baseline levels of platelet CD62P and CD63 were significantly enhanced at 28°C compared with 37°C. Expression was significantly increased at 28°C after stimulation with ADP, PAF and TRAP but not after stimulation with U46619. Overall, our results demonstrate an enhancement of platelet function at 28°C compared with 37°C, particularly in the presence of ADP.

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

10.1055/s-0039-1684468 ◽

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.

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

Thrombosis and Haemostasis ◽

10.1055/s-0038-1653698 ◽

1971 ◽

Vol 26 (03) ◽

pp. 455-466 ◽

Cited By ~ 1

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.

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Activation of human platelets by immune complexes prepared with cationized human IgG

Blood ◽

10.1182/blood.v82.10.3045.3045 ◽

1993 ◽

Vol 82 (10) ◽

pp. 3045-3051 ◽

Cited By ~ 12

Author(s):

M Schattner ◽

M Lazzari ◽

AS Trevani ◽

E Malchiodi ◽

AC Kempfer ◽

...

Keyword(s):

Platelet Aggregation ◽

Platelet Activation ◽

Immune Complexes ◽

Platelet Rich Plasma ◽

Human Platelets ◽

Human Igg ◽

Experimental Conditions ◽

Induce Platelet Aggregation ◽

Soluble Immune Complexes ◽

High Concentrations

Abstract The present study shows that the ability of soluble immune complexes (IC), prepared with human IgG and rabbit IgG antibodies against human IgG, to trigger platelet activation was markedly higher for IC prepared with cationized human IgG (catIC) compared with those prepared with untreated human IgG (cIC). CatIC induced platelet aggregation and adenosine triphosphate release in washed platelets (WP), gel-filtered platelets (GFP), or platelet-rich plasma (PRP) at physiologic concentrations of platelets (3 x 10(8)/mL) and at low concentrations of catIC (1 to 30 micrograms/mL). On the contrary, under similar experimental conditions, cIC did not induce aggregation in PRP, WP, or GFP. Low aggregation responses were only observed using high concentrations of both WP (9 x 10(8)/mL) and cIC (500 micrograms/mL). Interestingly, catIC were also able to induce platelet activation under nonaggregating conditions, as evidenced by P-selectin expression. Cationized human IgG alone did not induce platelet aggregation in PRP but triggered either WP or GFP aggregation. However, the concentration needed to induce these responses, was about eightfold higher than those required for catIC. The responses induced either by catIC or cationized human IgG were completely inhibited by treatment with heparin, dextran sulphate, EDTA, prostaglandin E1, or IV3, a monoclonal antibody against the receptor II for the Fc portion of IgG (Fc gamma RII). The data presented in this study suggest that IgG charge constitutes a critical property that conditions the ability of IC to trigger platelet activation.

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Evaluation of Highly Purified Bovine F. VIII and Bovine Plasma as Reagents to Induce Platelet Aggregation

10.1055/s-0039-1680433 ◽

1977 ◽

Author(s):

M. A. Lazzari ◽

C. Simonetti ◽

G. Casillas ◽

M. Pavlovsky

Keyword(s):

Platelet Aggregation ◽

Optical Density ◽

Sodium Citrate ◽

Platelet Rich Plasma ◽

Human Platelets ◽

Induce Platelet Aggregation ◽

Bovine Plasma ◽

Aggregation Factor ◽

High Concentrations

Purified bovine F. VIII is a known reagent for human platelets aggregation used for the study of thrombopaties. As bovine plasma (BP)is easier to prepare and standardize it was studied as an alternative reagent, comparing it with purified bovine F. VIII. Platelet aggregation was studied by a turbidimetric technique(Aggregometer Bryston AG 1). The substrates were platelet rich plasma (PRP)and gel filtered platelets using between 150,000 and 200,000 platelets/mm3 to standardize the platelets surface. 1/10 dilution of bovine plasma was found to be the best for PRP and 1/1 for filtered platelets. Incubation of the substrates with bovine plasma at 37°C for 5 min seems to enhance PAF activity of the platelet aggregation factor (PAF). Primary aggregation was obtained in PRP treated with 2% tetrasodic EDTA, 3. 4% sodium citrate and in plasma with aspirin. No secondary aggregation was observed in EDTA or aspirin plasma. Unlike platelets treated with ADP, their shape did not change since the optical density was not modified. No synergism or competition between PAF and ADP or adrenalin were found. High concentrations of NaCl or urea interfere with PAF, and esposure to 56°C inactivates it. In 50 normal PRP the percentage of total aggregation were: BP 1/10 42% ± 12 ; BP 1/1 79% ± 13 ;purified bovine F. VIII 1/10 86% ± 6 and in 10 batches of filtered platelets bp 1/1 82% ± 7. We consider an advantage to use bovine plasma for platelets aggregation studies.

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Inhibition of Thrombin-, Epinephrine- and Collagen-Induced Platelet Aggregation by α1-Acid Glycoprotein

10.1055/s-0039-1687235 ◽

1979 ◽

Author(s):

P. Andersen ◽

C. Eika

Keyword(s):

Platelet Aggregation ◽

Platelet Rich Plasma ◽

Adenosine Diphosphate ◽

Inhibitory Effect ◽

Human Platelets ◽

Clotting Time ◽

Acid Glycoprotein ◽

High Concentrations ◽

Spontaneous Platelet Aggregation ◽

Induced Aggregation

α1-Acid glycoprotein (α1,-acid GP) isolated from human plasma was found to inhibit thrombin-induced aggregation of washed human platelets (0.05 NIH U/ml final conc.), and inhibition was complete with physiological concentrations of α1-acid GP (1.0-1.5 g/1 final conc.). The inhibitory effect seemed to occur immediately on thrombin addition, thus similar to the effect of heparin previously observed. As opposed to heparin, however, α1-acid GP did not affect spontaneous platelet aggregation. Furthermore, α1-acid GP (in optimal cone.) reduced the combined inhibitory effect of heparin and antithrombin III on thrombin-induced platelet aggregation, thus consistent with the previous findings using heparin thrombin clotting time.Snyder and Coodley (1976) found α1-acid GP to inhibit platelet aggregation induced by epinephrine and adenosine diphosphate in platelet-rich plasma. As we also found α1-acid GP to inhibit collagen-induced platelet aggregation, α1-acid GP may possibly act as an inhibitor of the release reaction though fairly high concentrations (10 mg/ml final cone.) was needed for complete inhibition.

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Chrono-lume® and Magnesium Potentiate Aggregation of Canine but not Human Platelets in Citrated Platelet-Rich Plasma

Thrombosis and Haemostasis ◽

10.1055/s-0037-1615159 ◽

1998 ◽

Vol 80 (07) ◽

pp. 176-180 ◽

Cited By ~ 7

Author(s):

Frances Shofer ◽

Carol Wojenski ◽

Urs Giger ◽

Mary Beth Callan

Keyword(s):

Platelet Aggregation ◽

Magnesium Sulfate ◽

Platelet Function ◽

Sodium Citrate ◽

Platelet Rich Plasma ◽

Human Platelets ◽

Function Defect ◽

Dose Dependent ◽

Aggregation Of Platelets

SummaryThe effects of Chrono-lume® (CL) and magnesium sulfate (Mg2+), a component of this luciferin-luciferase reagent, on platelet aggregation were studied in platelet-rich plasma (PRP) obtained from blood anticoagulated with sodium citrate from humans, dogs, cats, horses, and cows. The final added Mg2+ concentration of both solutions ranged from 0.75-3.7 mM. CL and Mg2+ had no effect on maximum aggregation of platelets from humans induced by sub-threshold concentrations of collagen and ADP. In contrast, addition of CL or Mg2+ to canine PRP resulted in a dose-dependent and equal potentiation of platelet aggregation in response to sub-threshold concentrations of collagen, ADP, and thrombin in normal and thrombopathic dogs. The effect of CL on platelet aggregation induced by sub-threshold concentrations of agonists was less pronounced and varied in other species according to the agonist. The reason for the marked difference in sensitivity of human and canine platelets to CL or Mg2+ is not clear, although a difference in releasable cation pools of the platelets from these two species has been recognized. Platelet aggregation studies of animals with suspected thrombopathias should be performed without CL to prevent masking of a platelet function defect.

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

Blood ◽

10.1182/blood.v108.11.395.395 ◽

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.

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