On the Action of Intravenously Applied Acetylsalicylic Acid (ASA) on Platelet Functions, a Kinetic Study

Rapid Action ◽

Vitro Effect ◽

Kinetics Of ◽

Platelet Functions

There is general agreement that ASA inhibits platelet aggregation, adhesion and release reactions when given orally. In the present study, 10 individuals received a single intravenous dose of 500 mg ASA to examine the kinetics of the influence on platelet functions. Blood was drawn prior to ASA and at intervals between 2 minutes and 72 hours after injection.Collagen induced platelet aggregation as well as PF 3 and PF 4 release started to decrease 2 minutes after ASA and reached a minimum after 1 hour. A full ASA effect could still be observed after 24 hours though ASA had disappeared from plasma by that time. Simultaneously, in-vitro examinations with ASA were carried out. ASA was added to fresh platelet rich plasma in a concentration correspondent to the in-vivo dose. The inhibition of platelet aggregation and PF 4 release had a lag time of 1 hour and was considerably less distinct than in vivo. No inhibition of PF 3 release could be observed. The results demonstrate a rapid action of ASA when given intravenously while the in-vitro effect is much less distinct. A probable explanation is a direct effect of ASA on the platelet membrane. The enhancement in vivo is supposed to be caused by splitting of the acetylic group from ASA.

The in Vivo and in Vitro Effect of Antihistamines on Platelet Aggregation

10.1055/s-0038-1649138 ◽

1973 ◽

Vol 30 (03) ◽

pp. 597-601 ◽

Cited By ~ 1

Author(s):

Peter C. Ungaro ◽

Thomas M. Beck ◽

William M. McCaa ◽

Edward J. Hershgold

Keyword(s):

Platelet Aggregation ◽

Platelet Rich Plasma ◽

Normal Volunteers ◽

Direct Addition ◽

Drug Concentrations ◽

Vitro Effect

SummaryThe effect of antihistamines on platelet aggregation was studied by examining the platelet rich plasma of subjects taking three representative classes of these drugs, as well as by studying the effect of direct addition of antihistamine to platelet rich plasma. Inhibition of aggregation by in vitro addition was obtained only with drug concentrations much greater than would usually be found in vivo. Platelet aggregation was unimpaired in normal volunteers taking standard doses of antihistamines.

Furosemide and Platelet Functions

10.1055/s-0039-1680748 ◽

1977 ◽

Author(s):

I.S. Chohan ◽

I. Singh ◽

J. Vermvlen ◽

M. Verstraete

Keyword(s):

Platelet Aggregation ◽

Ex Vivo ◽

Metabolic Effects ◽

Platelet Factor ◽

Metabolic Products ◽

Vitro Effect ◽

Primary Platelet ◽

Platelet Functions

Furosemide inhibits primary platelet aggregation by adenosine-5'-diphosphate and prolongs the latent period before Thrombofax- or collagen-induced platelet aggregation, both in vitro and ex vivo. Furosemide also inhibits the release of platelet factor 4 and 14C-serotonin. The inhibitory concentrations of furosemide in vitro range between 0.5 and 2.5 mM. The ex vivo effects were obtained after an intravenous injection of 40 mg furosemide.The furosemide concentrations required for ex vivo inhibition are hundred fold lower than those required for in vitro effect. This suggests in vivo metabolic effects of this drug, such as, calcium ions shifts, or action of other metabolic products of furosemide. In support of this concept platelet aggregation was found more disturbed six hours than 10 minutes after injection of the drug.

Inhibition of platelet aggregation and thromboxane production by low concentrations of aspirin in vitro

Clinical Science ◽

10.1042/cs0740491 ◽

1988 ◽

Vol 74 (5) ◽

pp. 491-497 ◽

Cited By ~ 12

Author(s):

D. Sils ◽

S. E. Rodgers ◽

J. V. Lloyd ◽

K. M. Wilson ◽

D. M. Siebert ◽

...

Keyword(s):

Platelet Aggregation ◽

Platelet Rich Plasma ◽

Critical Concentration ◽

Significant Inhibition ◽

Inhibit Platelet Aggregation ◽

Prolonged Incubation ◽

Low Concentrations

1. The aspirin concentrations previously reported to inhibit platelet aggregation in vitro (40–500 μmol/l) are much greater than those required in vivo in man (5 μmol/l). 2. Human platelet-rich plasma was incubated with buffer or various aspirin concentrations at 37°C for up to 4.5 h. Platelet aggregation and thromboxane generation were measured in response to collagen (0.4–6.3 μg/ml) and adenosine 5′-pyrophosphate (0.5–4 μmol/l). 3. The concentration of aspirin needed to inhibit platelet aggregation in response to a critical concentration of aggregating agent (lowest concentration to cause greater than 50% aggregation) was lower than that required for higher concentrations of aggregating agent. 4. With more prolonged incubation times with aspirin, lower concentrations of aspirin inhibited platelet aggregation. 5. Inhibition of platelet aggregation and thromboxane formation by 10 μmol/l aspirin was maximal by 90 min. There was progressive inhibition by 3 μmol/l aspirin during incubation for 270 min. By the end of this time there was also significant inhibition by 1 μmol/l aspirin. 6. The apparent discrepancy between inhibitory aspirin concentrations in vivo and those observed in vitro in previous studies appears to have been resolved by extending the incubation time of platelets with low aspirin concentrations, thus mimicking the conditions in vivo.

THE PLATELET ANTIAGGREGATORY EFFECT OF ILOPROST IS ENHANCED BY ASPIRIN:IN VITRO AND EX VIVO STUDIES IN HUMAN SUBJECTS.

10.1055/s-0038-1643453 ◽

1987 ◽

Author(s):

E Tremoli ◽

P Maderna ◽

S Colli ◽

L Mannucci ◽

C R Sirtori ◽

...

Keyword(s):

Platelet Aggregation ◽

Ex Vivo ◽

Platelet Rich Plasma ◽

Human Subjects ◽

Selective Inhibition ◽

Blood Collection ◽

Iloprost Infusion

To evaluate whether the activity of Iloprost, a chemically stable prostacyclin analog, on platelet aggregation could be potentiated by aspirin (ASA), in vitro and ex vivo studies in human volunteers were performed. In vitro studies were carried out in human platelet rich plasma (PRP) incubated with different concentrations of ASA (25-150 μM). For ex vivo studies Iloprost (0.5 ng.Kg−1.min−1 for 30 min) was given intravenously to healthy volunteers. After 20 hour wash out a single 50 mg ASA dose was given to the same subjects. Two hours after ASA intake, a second infusion of Iloprost was carried out. Blood was collected at appropriate time intervals thereafter. Platelet aggregation and thromboxane B2 (TXB2) formation were determined in collagen stimulated PRP. ASA, in vitro , dose dependently reduced the concentrations oF Iloprost required to achieve 50% inhibition of platelet aggregation (IC50) in PRP stimulated by 1 g/ml collagen. Also, the IC50S for Iloprost were significantly reduced (p<0.01) in PRP of subjects who ingested ASA two hours before blood collection. Iloprost infusion (0.5 ng.Kg−1.min−1 for 30 min) only minimally affected the concentrations of collagen eliciting 50% aggregation (AC50) and was ineffective on TXB2 synthesis. ASA, administered after a 20 hour wash out period did not significantly affect the AC s for collagen, whereas it inhibited TXB2 synthesis by more than 50%. The mean AC50 for collagen, evaluated at the end of Iloprost infusion in PRP of subjects who previously ingested ASA, was signicantly greater than that evaluated after the two single treatments. No significant changes in hemodynamic and ECG parameters were detected during the study. These findings, indicating an in vivo potentiating effect of ASA on the antiaggregatory activity of Iloprost, observed at doses of Iloprost with no effect on hemodynamic parameters, may be of relevance for the design of treatment schedules aimed to the selective inhibition of platelet aggregation.

Inhibition Of Platelet Aggregation

Inhibition of Platelet Aggregation by Brinolase Degradation Products of Fibrinogen and Serum Albumin

10.1055/s-0039-1680556 ◽

1977 ◽

Author(s):

W. H. E. Roschlau

Keyword(s):

Platelet Aggregation ◽

Serum Albumin ◽

Degradation Products ◽

Platelet Rich Plasma ◽

Biological Effects ◽

Response Curves ◽

Human Fibrinogen ◽

Brinolase (fibrinolytic enzyme from Aspergillus oryzae) was observed to possess significant platelet aggregation inhibitory properties during and after thrombolytic therapeutic use. These platelet effects were found in vitro to be caused in part by intermediate products of fibrinogen digestion, namely low-molecular-weight peptides of approx. MW 2500. Human fibrinogen peptides were isolated, purified, and shown to have high inhibitory activity in platelet-rich plasma. Quantitative comparisons of attainable platelet inhibition in vitro and observed responses in vivo during administration of equivalent enzyme doses, however, suggested that total available fibrinogen, even if it were entirely converted to degradation products (which it is not), would be insufficient to account for observed platelet effects of brinolase therapy.Human serum albumin is also readily degraded by brinolase. Albumin degradation products were prepared in vitro by optimal incubation with the enzyme. Dose-response curves of inhibition of platelet aggregation were obtained with lyophilized peptides in platelet-rich plasma in vitro, and significant inhibition of platelet aggregation was observed in vivo following infusion of albumin degradation products into rabbits. The enzyme doses and amounts of substrates employed in all experiments were equivalent to the conditions of therapeutic fibrinolysis.Thus, albumin degradation products are considered to contribute a significant, if not the major, portion of platelet-active intermediates during clinical brinolase therapy. Albumin cleavage, which is unique to brinolase amongst clinical fibrinolytic enzymes, was shown to have biological effects of its own, but it may also serve to protect coagulation proteins from enzymatic destruction through competition for the enzyme during systemic brinolase therapy.

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

10.1055/s-0038-1647788 ◽

1973 ◽

Vol 29 (02) ◽

pp. 490-498 ◽

Cited By ~ 6

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.

Effects of Halothane on Platelet Function

10.1055/s-0038-1650105 ◽

1980 ◽

Vol 44 (03) ◽

pp. 143-145 ◽

Cited By ~ 19

Author(s):

J Dalsgaard-Nielsen ◽

J Gormsen

Keyword(s):

Platelet Aggregation ◽

Platelet Function ◽

Platelet Rich Plasma ◽

Human Platelets ◽

Halothane Anaesthesia ◽

Transient Impairment ◽

High Concentrations ◽

Uptake And Release ◽

Platelet Functions

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.

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

10.1055/s-0038-1649080 ◽

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.

Are Platelet Aggregation Tests the Best Way to Assess New Drugs for Arterial Disease

General medicine and Clinical Practice ◽

10.31579/2639-4162/003 ◽

2018 ◽

Vol 1 (1) ◽

pp. 01-03

Author(s):

Mark I. M. Noble

Keyword(s):

Platelet Aggregation ◽

Platelet Function ◽

Platelet Rich Plasma ◽

New Drugs ◽

In Vitro Test ◽

In Vivo Efficacy ◽

Experimental Animals ◽

Stenosed Artery

Over many years, laboratory testing of platelet aggregability have been carried out in attempts to develop drugs that would prevent thrombosis in arteries. The problems encountered included the question of methodology. Blood samples have to be anticoagulated in order to study the platelets. Anti-coagulation with citrate and tests on derived platelet rich plasma did not correlate at all well with thrombus growth in the stenosed coronary arteries of experimental animals and citrate removes the calcium ions which are vital for platelet function. Anticoagulation with heparin also interfered with platelet function, so that now, hirudins are the preferred anticoagulant. However it was observed that if, instead of stimulating platelet aggregation with adrenaline or ADP, serotonin was applied to the preparation, very little aggregation took place in spite of serotonin 5HT2A antagonists being the most potent inhibitors of thrombus growth in experimental animals. Another indicator that primary platelet agggregation is not a predictor of in vivo efficacy was the finding that 5HT2A antagonism inhibited aggregate growth. In a stenosed artery the platelets are activated by increased shear stress and blood turbulence with release of platelet serotonin causing positive feedback activation of more platelets. At present, there does not seem to be a bench in vitro test that accurately predicts in vivo efficacy in stenosed artery occlusive thrombosis.

Arginine vasopressin release from human platelets after irreversible aggregation

Clinical Science ◽

10.1042/cs0780113 ◽

1990 ◽

Vol 78 (1) ◽

pp. 113-116 ◽

Cited By ~ 7

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.