scholarly journals 3’5’-Adenosine Diphosphate (3′5′ADP):A Physiological Inhibitor of Platelet Aggregation and Platelet Release Reaction

1977 ◽  
Author(s):  
K. Subbarao ◽  
K. Jaya
Keyword(s):  
Platelet Aggregation ◽  
Coenzyme A ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Serotonin Release ◽  
Dependent Manner ◽  
Release Reaction ◽  
Inhibition Of Platelet Aggregation ◽  
Vitro Effect ◽  
Aggregation Of Platelets

Certain analogues of adenosine have been shown to inhibit ADP-induced platelet aggregation. We therefore studied the in vitro effect of 3′5′ADP and coenzyme A on human platelet aggregation and [14C]-serotonin release reaction induced by the addition of ADP, thrombin, collagen and epinephrine to human platelet rich plasma (PRP). It was found that coenzyme A Li3·2H2O at a concentration of 0.12 mM strongly inhibited ADP-induced platelet aggregation of PRP but did not show similar effect on the aggregation of platelets induced by other aggregating agents. The 3′5′ADP which is a part of coenzyme A structure, on the other hand, inhibited both ADP and thrombin induced platelet aggregation. The extent of inhibition of platelet aggregation by coenzyme A and 3′5′ADP was found to depend upon the concentration of the inhibitor and the incubation time. Whereas 3′5′ADP Li2·3H2O at a concentration of 10 μM produced about 70% inhibition of ADP-induced platelet aggregation of human PRP, total inhibition of thrombin induced platelet aggregation was observed when platelets were incubated with 60 μM of 3′5′ADP. The 3′5′ADP also inhibited the [14C]-adeonsine uptake by platelets in a concentration dependent manner. The inhibitory potency of 3′5′ADP on platelet aggregation was found to be 10-fold higher than that of N6-2′-0-dibutyryl-cyclic 3′5′-adenosine monophosphate. The inhibition of platelet aggregation by coenzyme A and 3′5′ADP was always accompanied by the inhibition of [14C]-serotonin release reaction. If coenzyme A and 3′5′ADP are indeed physiological inhibitors of platelet aggregation, then aggregation of platelets should depend on metabolic events that regulate the concentration of these agents in blood.

scholarly journals Inhibitory Effect of Diamines and Polyamines on Human Platelet Aggregation and [14C]-Serotonin Release Reaction

1977 ◽  
Author(s):  
K. Subbarao ◽  
F. Forestier
Keyword(s):  
Platelet Function ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Serotonin Release ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Release Reaction ◽  
Aggregation Of Platelets

Physiological diamines and polyamines occur in high concentrations in various parts of animal tissues. These amines are known to interact with and stabilize nucleic acids, membranes and ribosomes (Tabor and Tabor, Pharmac. Rev., 16, 245). The effect of putrescine, cadaverine, spermidine and spermine on platelet function is not yet fully explored. We studied the effect of these reagents on in vitro aggregation of human platelet rich plasma (PRP) induced by the addition of ADP, thrombin, collagen and serotonin. Cadaverine, spermidine and spermine at concentrations from 2-5 μM strongly inhibited the aggregation of platelets and the [14C]-serotonin release reaction induced by ADP and thrombin in a concentration dependent manner, but did not show any effect on aggregation induced by other agents. Putrescine, on the other hand, failed to produce any effect on the aggregation of platelets and [14C]-serotonin release reaction. Studies on the binding of purified human thrombin treated with [14C]-diisopropylfluoro-phosphate (DFP) to washed human platelets indicated that cadaverine (1-5 μmoles) increased the binding of total [14C]-DFP-thrombin to platelets by 30%. The data suggest that the alteration of platelet function by diamines and polyamines was probably achieved by their binding to platelet membranes.

Platelet Aggregation By Membrane Glycoprotein I

1981 ◽  
Author(s):  
K Watanabe ◽  
M Yamamoto ◽  
Y Ando ◽  
H Iri ◽  
K Furihata ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Lag Phase ◽  
Affinity Column ◽  
Membrane Glycoprotein ◽  
Dependent Manner ◽  
Membrane Glycoproteins ◽  
Aggregation Mechanism ◽  
Membrane Components ◽  
Aggregation Of Platelets

It has been recently shown that platelet membrane components, particularly glycoproteins, have a lectin activity, thus mediating an aggregation of platelets. To obtain further evidences for a crucial role of glycoproteins in an aggregation mechanism,we have investigated the possibility that membrane glycoprotein can directly induce an aggregation of platelets. The membrane glycoproteins ( GP I, GP II and GP III ) were isolated from 3-4 mg of human platelet membranes using preparative electrophoresis on 5 % polyacrylamide gels with 0.1% SDS. Platelet aggregation by isolated GP I, GP II or GP III was examined under phase_contrast microscopy after the incubation of these peptides with platelet rich plasma at 37°C for 15 min.. Among glycoproteins tested, only GP I( 20 μg/ml < ) exerted an apparent platelet aggregation. No such aggregation was induced by either GP II or GP III even at concentration of 80 μg/ml. GP I isolated separately using the wheat germ agglutinin affinity column also produced a platelet aggregation. Aggregation curve recorded with an aggregometer showed a long lag phase ( 10 min. < ) followed by an irreversible aggregation. The GP I-induced platelet aggregation occured in a dose dependent manner. This aggregation was completely inhibited by the addition of aggregating inhibitors such as indomethacin ( 25 μM ), PGE1 ( 1 μM ), EDTA ( 0.5 mM ) and TMB-8 ( lmg/ml ). A significant amount of serotonin ( 27% ) and β-thromboglobulin ( 14.6% ) was released from platelets by GP I ( 100 μg/ml ). Treatment of GP I with either trypsin ( 50 μg/ml ) or chymotrypsin ( 40 μg/ml ) reduced the aggregating activity of this glycopeptides. The platelet aggregation by GP I was inhibited in the presense of 30 mM N-acetylneuraminic acid, arginin or L-lysine, but N-acetyl- ated amino sugars and neutral sugars were without effect. This GP I-induced platelet aggregation may be an important findings in elucidating platelet aggregation mechanism.

scholarly journals Both Complement- and Fibrinogen-Dependent Mechanisms Contribute to Platelet Aggregation Mediated by Staphylococcus aureus Clumping Factor B

2007 ◽  
Vol 75 (7) ◽  
pp. 3335-3343 ◽  
Author(s):  
Helen Miajlovic ◽  
Anthony Loughman ◽  
Marian Brennan ◽  
Dermot Cox ◽  
Timothy J. Foster
Keyword(s):  
Staphylococcus Aureus ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Lag Time ◽  
Dependent Manner ◽  
Wild Type ◽  
Factor B ◽  
Fibrinogen Binding ◽  
Aggregation Of Platelets ◽  
Dependent Mechanism

ABSTRACT Staphylococcus aureus can stimulate activation and aggregation of platelets, which are thought to be factors in the development of infective endocarditis. Previous studies have identified clumping factor A (ClfA) and fibronectin binding proteins A and B (FnBPA and FnBPB) as potent platelet aggregators. These proteins are able to stimulate rapid platelet aggregation by either a fibrinogen- or a fibronectin-dependent process which also requires antibodies specific to each protein. Slower aggregation has been seen in other systems where specific fibrinogen binding ligands are absent and platelet aggregation is mediated by complement and specific antibodies. Bacteria expressing ClfB aggregate platelets with a longer lag time than ClfA or FnBPA and FnBPB. In order to investigate whether ClfB causes platelet aggregation in a complement- or fibrinogen-dependent manner, a non-fibrinogen-binding mutant of ClfB (ClfB Q235A) was constructed. Lactococcus lactis expressing ClfB Q235A was able to stimulate platelet aggregation in platelet-rich plasma without a significant increase in lag time. The requirements for platelet aggregation were investigated using gel-filtered platelets. Fibrinogen and specific anti-ClfB antibodies were found to be sufficient to allow platelet aggregation mediated by the wild-type ClfB protein. It seems that ClfB causes platelet aggregation by a fibrinogen-dependent mechanism. The non-fibrinogen-binding ClfB mutant was unable to stimulate platelet aggregation under these conditions. However, bacteria expressing ClfB Q235A caused platelet aggregation in a complement-dependent manner which required specific anti-ClfB antibodies.

Dipyridamole (D) Reduces the Effectiveness of Prostaglandin (PG) I2. PGD2 and PGE1 as Inhibitors of Platelet Aggregation in Human Platelet-Rich Plasma (PRP)

1979 ◽  
Author(s):  
Di G. Minno ◽  
de G. Gaetano ◽  
M.J. Silver
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Concentration ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Mechanisms Of Action ◽  
Phosphodiesterase Activity ◽  
Inhibition Of Platelet Aggregation ◽  
Normal Humans ◽  
The Mean

The effectiveness and the mechanism of action of D as an anti-thrombotic agent has been controversial. It has been proposed that D works by potentiating the inhibitory activity of "circulating" PGE2 on platelet aggregation by inhibiting platelet phosphodiesterase activity. To determine whether such potentiation exists in normal humans we studied inhibition of aggregation by the PGs in PRP before and 90 mln after the ingestion of D (100 mg). As expected, we found that the threshold aggregating concentrations of ADP, collagen and arachidonic acid (AA) were unchanged after the ingestion of D. Unexpectedly, the threshold inhibitory concentration of each PG was greater after ingestion of D than before. The mean elevations for PGI2 were 8.8 nM (p<0.05) vs ADP; 9.1 nM(p<0 01) ys collagen; 9.2 nM (p<0.001) vs AA; for FCD2 14.5 nM (p<0.05) vs AA; for PGE, 69 0 nM (p<0.05) vs collagen and 25.9 nM (p<0.05) vs AA. The elevations for PGD2 vs ADP and collagen and for PGE1 vs ADP were not significant. These data do not support the hypothesis that D aces as an anti-thrombotic agent by potentiating the inhibition of platelet aggregation by “circulating” PGIZ. The findings show that ingestion of D Interferes with the inhibitory effect of the PGs and suggest that other mechanisms of action ot D should be investigated.(Supported by the Italian CNR and NIH).

scholarly journals Inhibition of platelet aggregation by protease inhibitors. Possible involvement of proteases in platelet aggregation

Blood ◽  
1978 ◽  
Vol 52 (1) ◽  
pp. 1-12 ◽  
Author(s):  
N Aoki ◽  
K Naito ◽  
N Yoshida
Keyword(s):  
Platelet Aggregation ◽  
Protease Inhibitors ◽  
Serine Proteases ◽  
Human Platelet ◽  
Serotonin Release ◽  
Second Phase ◽  
Inhibition Of Platelet Aggregation ◽  
Naturally Occurring ◽  
Human Platelet Aggregation ◽  
Platelet Receptor

Abstract The possible participation of proteases in human platelet aggregation was explored using various protease inhibitors and substrates. Protease inhibitors used included naturally occurring inhibitors of serine proteases and synthetic inhibitors that modify the active site of protease. Substrates used were synthetic substrates for the trypsin type as well as for the chymotrypsin type of protease. All these inhibitors and substrates inhibited platelet aggregation and serotonin release induced by ADP, collagen, epinephrine, or thrombin. In ADP- and epinephrine-induced platelet aggregation the second phase of aggregation was most efficiently inhibited. The inhibitors suppressed the formation of malondialdehyde during platelet aggregation. Release by aggregating agents of arachidonate and its metabolites from indomethacin-treated platelets as well as nontreated platelets was also inhibited. The inhibitors apperar to interact with stimulated platelets but not with unstimulated platelets. These observations suggest that the interaction of an aggregating agent with its platelet receptor activates a unique precursor serine protease that in turn activates platelet phospholipase to liberate arachidonic acid (the precursor of the potent platelet aggregating agent thromboxane A2) from platelet phospholipids.

scholarly journals The Effect of Cold on Platelets. II. Platelet Function After Short-term Storage at Cold Temperatures

Blood ◽  
1972 ◽  
Vol 40 (5) ◽  
pp. 688-696 ◽  
Author(s):  
Herman E. Kattlove ◽  
Benjamin Alexander ◽  
Frances White
Keyword(s):  
Platelet Aggregation ◽  
Room Temperature ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
Serotonin Release ◽  
Prolonged Storage ◽  
Cold Temperatures ◽  
Aggregation Of Platelets ◽  
Term Storage

Abstract Citrated platelet-rich plasma (PRP) was kept at cold temperatures or room temperature. After 4 hr or more at these temperatures, the PRPs were warmed 1 hr at 37°C. This prevents the spontaneous aggregation seen in chilled PRP that is stirred immediately after warming. Platelet aggregation in response to connective tissue (CT), epinephrine, and adenosine diphosphate (ADP) was considerably greater in the PRPs originally kept at cold temperatures. In addition, chilling would restore the aggregation of platelets whose function had deteriorated due to prolonged storage at warm temperatures. Neither ADP-induced refractoriness, serotonin uptake, or CT-induced serotonin release was affected by cold. Retention in glass bead columns was greater in platelets that had been chilled than in platelets kept at room temperature or 37°C. Thus, the storage of platelets at cold temperatures leads to changes that improve platelet aggregation but may also increase platelet adhesion, which would account for the decreased in vivo survival of platelets preserved for transfusion at cold temperatures.

Effect of Lidoflazine (R 7904) on Human Platelet Function in Vitro

1972 ◽  
Vol 28 (02) ◽  
pp. 228-236 ◽  
Author(s):  
F De Clerck
Keyword(s):  
Platelet Function ◽  
Mode Of Action ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Serotonin Release ◽  
Clot Retraction ◽  
Plasma Coagulation ◽  
Release Reaction ◽  
Platelet Release

SummaryThe effect of lidoflazine and of cinnarizine on human platelet function in vitro was compared to that of dipyridamole.Pre-incubation for 30 min at 37° C of platelet rich plasma with lidoflazine or with dipyridamole 5 ×10–4 M resulted in an appreciable inhibition of collagen aggregation in particular and to a lesser extent of ADP aggregation; cinnarizine was marginally active only.Clot retraction was inhibited by lidoflazine and by dipyridamole. Experiments on biphasic ADP aggregation and C14-serotonin release during aggregation show that lidoflazine reduces the platelet release reaction.The possible mode of action of the compound is discussed.Plasma coagulation and PF – 3 availability were not affected.

Inhibition of ADP-Induced Platelet Aggregation by Adenosine Tetraphosphate

1976 ◽  
Vol 36 (02) ◽  
pp. 388-391 ◽  
Author(s):  
Margaret J. Harrison ◽  
R Brossmer
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Platelet Rich Plasma ◽  
Release Reaction ◽  
Induced Aggregation ◽  
Aggregation Of Platelets

SummaryIn contrast to previous reports, highly purified adenosine tetraphosphate (AP4) does not induce the aggregation of platelets but inhibits the aggregation and release reaction in platelet-rich plasma promoted by ADP. The inhibitory action of AP4 on the aggregation by ADP is compared with that of AMP and ATP. The data presented suggest a competitive manner of inhibition of the ADP-induced aggregation by AP4.

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

1971 ◽  
Vol 26 (03) ◽  
pp. 455-466 ◽  
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.

Comparisons of Biochemical and Pharmacological Properties of Prostacyclins with Modified ω-Side Chain

1979 ◽  
Author(s):  
K. U. Weithmann ◽  
W. Bartmann ◽  
G. Beck ◽  
U. Lerch ◽  
E. Konz ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Systemic Blood Pressure ◽  
Side Chain ◽  
Adenylate Cyclase System ◽  
Dependent Manner ◽  
High Biological Activity ◽  
Structure Activity ◽  
Dose Dependent

PGI2-analogs in which the n-pentyl moiety in position 15 was replaced by several residues, were subjected to structure-activity studies. Some of the modified PGI2’s showed remarkable potency in regard to antiplatelet and vasodilator actions. in order to evaluate these potencies the inhibition of arachidonic acid induced platelet aggregation in human platelet rich plasma, relaxation of bovine coronary artery (BCA) and systemic blood pressure (BP) in the anesthetized rat were determined. Platelet aggregation was inhibited by PGI2 with an IC50 approx. 3-10-9M, BP was decreased in a dose dependent manner with an ED25, of 0.23 ug/kg i.v. and a marked relaxation of BCA was observed. Similar results were obtained with PGI2-methylester. Substitution of the n-pentyl moiety by cyclohexyl, 3-furyl-2-ethyl or 3-thienyl-oxymethyl resulted in PGI2- and PGI2-methyl-ester-analogs with high biological activity, whereas substitution by T6,16-dimethyl-18-oxa-alkyl or phenoxymethyl caused a loss of activity in the models used. The potency of the prostacyclins in the platelet model seem to depend upon their ability to elevate the platelet cyclo-AMP level. Thus the antiplatelet potency of modified PGI2’s may reflect their ability to affect the adenylate cyclase system.

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