Effects of hydrostatic pressure and inert gases on platelet aggregation in vitro

1990 ◽  
Vol 69 (6) ◽  
pp. 2239-2247 ◽  
Author(s):  
D. M. Pickles ◽  
D. Ogston ◽  
A. G. Macdonald
Keyword(s):  
Platelet Aggregation ◽  
Hydrostatic Pressure ◽  
Maximum Degree ◽  
Platelet Rich Plasma ◽  
Control Level ◽  
Inert Gases ◽  
Partial Pressures ◽  
Compression Cycle ◽  
Anesthetic Potency

A novel cuvette was used to subject citrated platelet-rich plasma (PRP) to high hydrostatic pressure with negligible contamination by He (used for compression of the apparatus). Aggregation was induced at pressure by ADP and quantified turbidimetrically. The maximum degree of aggregation (MDA) was reduced from a control level of 82.2 to 53.6% by exposure to 101 ATA. Because decompression bubbles did not form, aggregation was also measured immediately after a compression cycle. After exposure to 101 ATA hydrostatic pressure, platelets responded normally to ADP at 1 ATA. In a matching apparatus, PRP was equilibrated with high partial pressures of inert gases. Normal physiological plasma Po2 and pH were maintained during equilibration. N2O (5 ATA) reduced the MDA from 86.5 (control) to 58.1%. N2 (51 ATA) reduced the MDA from 74.7 (control) to 51.6%, and 101 ATA Pn2 reduced the MDA from 78.0 (control) to 32.3%. He (100 ATA) reduced the MDA from 83.6 to 38.6%. It was concluded that platelet aggregation was relatively sensitive to hydrostatic pressure and less sensitive to inert gases than predicted from their anesthetic potency ratios.

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.

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.

A Thiazole Compound with Potential Antithrombotic Activity

1982 ◽  
Vol 47 (02) ◽  
pp. 173-176 ◽  
Author(s):  
E E Nishizawa ◽  
A R Mendoza ◽  
T Honohan ◽  
K A Annis
Keyword(s):  
Platelet Aggregation ◽  
Potent Inhibitor ◽  
Platelet Rich Plasma ◽  
Development Program ◽  
Antithrombotic Agent ◽  
Antithrombotic Activity ◽  
Thiazole Derivative ◽  
Cyclooxygenase Activity ◽  
Drug Development Program

SummaryA thiazole derivative, 4,5-bis(p-methoxyphenyl)-2-(trifluoromethyl)-thiazole was found to be a potent inhibitor of collagen-induced platelet aggregation, in vitro, using platelets from at least six species, including man. It was active in human platelet-rich plasma at a concentration of 1 ng/ml. While its antiplatelet activity was greater than that of flurbiprofen, its cyclooxygenase activity was equivalent to that of flurbiprofen. Also, compared to flurbiprofen, the thiazole had less anti-inflammatory activity in the hind-paw edema test. The thiazole derivative inhibited platelet aggregation following oral administration in five laboratory species. In the guinea pig it was active at 0.5 mg/kg. The LD50 in mice was greater than 1000 mg/kg (i.p.). This compound, which was designed through a systematic drug development program, may have high potential as an antithrombotic agent.

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.

Decreased Platelet Vitamin C in Diabetes Mellitus; Possible Role in Peraggregatoon

1979 ◽  
Author(s):  
K.E. Sarji ◽  
J. Gonzalez ◽  
H. Hempling ◽  
J.A. Colwell
Keyword(s):  
Ascorbic Acid ◽  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Vitamin C ◽  
Platelet Rich Plasma ◽  
Solution Ph ◽  
Dose Dependent Fashion ◽  
Insulin Dependent Diabetic ◽  
Induced Aggregation

To determine whether Vitamin C might relate to the increased platelet sensitivity in the diabetic, we have measured levels of platelet Vitamin C and studied the effects of Vitamin C on platelet aggregation. Ascorbic acid levels in washed platelets from diabetics were significantly lower than from normals (4s.2±3 μg/1010 platelets vs. 2s.s±2 μg/1010 platelets, p<.001). The effects of ascorbic acid on platelet aggregation in vitro were studied by adding ascorbic acid in buffered solution (pH 7.35) prior to-aggregating agents. Ascorbic acid in platelet-rich plasma consistently inhibited platelet aggregation with threshold concentrations of ADP, epinephrine, and collagen. With washed platelets, ascorbic acid inhibited arachidonic, acid-induced aggregation. When platelets were incubated at 37°C for 10 minutes with varying concentrations of ascorbic acid, rewashed, and aggregation with arachidonic acid tested, aggregation was inhibited in a linear dose-dependent fashion. Oral ingestion of ascorbic acid (2 gm/day) for seven days by normal non-smoking males produced a marked inhibition of aggregation. In a similar study, platelets from an insulin-dependent diabetic showed no change in aggregation. These results suggest that platelet levels of ascorbic acid may relate to the hyperaggregat ion of platelets from diabetics.

Modified Technique for Measuring Platelet Aggregation

1997 ◽  
Vol 3 (3) ◽  
pp. 196-202 ◽  
Author(s):  
Alexander Kaplan ◽  
Svetlana Kaplan ◽  
Karen F. Marcoe ◽  
Lester R. Sauvage ◽  
William P. Hammond
Keyword(s):  
Platelet Aggregation ◽  
Citric Acid ◽  
Platelet Rich Plasma ◽  
Antiplatelet Agents ◽  
Current Approach ◽  
Molar Ratio ◽  
Maximum Height ◽  
Modified Technique ◽  
Aggregation Pattern

The turbidimetric method of Bom is the current approach for assessing the aggregation behavior of platelets. It has been of modest practical value, due to difficulty in standardizing laboratory techniques for plasma preparation and inadequate quantification of the aggregation process. We report a new technique of sedimented platelet rich plasma (SPRP) preparation that reduces the irregularities caused by factors associated with procuring and preparing blood samples and permits a more flexible protocol for laboratory practice. We quantified results with a platelet aggregation score, which is calculated by multiplying the ratio of the height of the initial wave of aggregation to the maximum height of the aggregation pattern by the total area under the aggregation curve and by the ratio of the whole blood platelet count and the number of platelets in the sample. Comparative analysis of platelet aggregation scores (n = 95) obtained with both plasma preparation techniques using a paired t test demonstrated no statistical differences ( t = 1.368, p = 0.174). To demonstrate the application of this modified method to evaluation of antiplatelet agents, the effects of aspirin and aspirin combined with citric acid on platelet aggregation were studied in vitro. The antiaggregatory effect of aspirin combined with citric acid was dependent on the pH and on their molar ratio, and was greater than the effect of aspirin alone. The SPRP protocol with platelet aggregation scoring methodology could be a valid alternative for measurement of the platelets' propensity to aggregate and the effect of antithrombotic treatments. Key Words: Platelet aggregation— Aspirin—Citric acid.

Effects of Ethanol on Pathways of Platelet Aggregation In Vitro

1988 ◽  
Vol 59 (03) ◽  
pp. 383-387 ◽  
Author(s):  
Margaret L Rand ◽  
Marian A Packham ◽  
Raelene L Kinlough-Rathbone ◽  
J Fraser Mustard
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Secondary Phase ◽  
Primary Phase ◽  
Rabbit Platelet ◽  
Membrane Phospholipids ◽  
Rabbit Platelets ◽  
Induced Aggregation

SummaryEthanol, at physiologically tolerable concentrations, did not affect the primary phase of ADP-induced aggregation of human or rabbit platelets, which is not associated with the secretion of granule contents. Potentiation by epinephrine of the primary phase of ADP-induced aggregation of rabbit platelets was also not inhibited by ethanol. However, ethanol did inhibit the secondary phase of ADP-induced aggregation which occurs with human platelets in citrated platelet-rich plasma and is dependent on the formation of thromboxane A2. Inhibition by ethanol of thromboxane production by stimulated platelets is likely due to inhibition of the mobilization of arachidonic acid from membrane phospholipids, as ethanol had little or no effect on aggregation and secretion induced by arachidonic acid or the thromboxane mimetic U46619. Rabbit platelet aggregation and secretion in response to low concentrations of collagen, thrombin, or PAF were inhibited by ethanol. Inhibition of the effects of thrombin and PAF was also observed with aspirin-treated platelets. Thus, in addition to inhibiting the mobilization of arachidonate for thromboxane formation that occurs with most agonists, ethanol can also inhibit aggregation and secretion through other effects on platelet responses.

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