Abstract 4023: Aspirin “Resistance”: Role of Pre-existent Platelet Reactivity and Correlation Between Tests

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Andrew L Frelinger ◽  
Youfu Li ◽  
Matthew D Linden ◽  
Inge Tarnow ◽  
Marc R Barnard ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Function ◽  
Normal Subjects ◽  
Aspirin Resistance ◽  
The Other ◽  
List Type ◽  
Platelet Function Test ◽  
Function Test

Background: Aspirin “resistance” (i.e. hyporesponsiveness to aspirin in a platelet function test) has been widely reported, but the underlying mechanism is unclear. We examined the role of pre-existent platelet hyperreactivity in aspirin “resistance”. We also determined the correlation between aspirin resistance defined by serum thromboxane (TX) B 2 (the most specific test of aspirin’s effect) and other assays of platelet function. Methods: Platelet function measured before and after aspirin 81 mg daily for 7 days was analyzed by Spearman’s rank correlation. Normal subjects (n=165) were studied because virtually all clinically relevant patients are already taking aspirin. An additional advantage of the use of normal subjects is that the platelet response to stimuli is not influenced (with resultant increased scatter of the data) by an underlying disease, e.g. coronary artery disease, which causes platelet hyperreactivity. Results: The proportion of the post-aspirin platelet function predicted by the pre-aspirin platelet function was 28.3 ± 7.5% (mean ± asymptotic standard error) for serum TXB 2 , 39.3 ± 6.8% for urinary 11-dehydro TXB 2 , 4.4 ± 7.7% for arachidonic acid-induced platelet aggregation, 40.4 ± 7.1% for ADP-induced platelet aggregation, 26.3 ± 9.2% for the VerifyNow Aspirin Assay®, and 45.0 ± 10.9% for the TEG® PlateletMapping ™ System with arachidonic acid. Spearman rank order correlations were highly significant for comparisons between assays when both pre-aspirin and post-aspirin results were included in the analysis. However, residual serum TXB 2 levels post-aspirin treatment were not significantly associated with post-treatment results of any of the other assays. Platelet count correlated with pre-aspirin serum TXB 2 and VerifyNow Aspirin Assay, but not with any post-aspirin platelet function test. Conclusions: Aspirin “resistance” (i.e. hyporesponsiveness to aspirin in a laboratory test) is in part unrelated to aspirin but is the result of underlying platelet hyperreactivity prior to the institution of aspirin therapy. Individuals identified as aspirin “resistant” defined by serum TXB 2 are not the same individuals identified by the other tests.

Comparison of Rapid Platelet Function Assay with Whole Blood Platelet Impedance Aggregometry for the Definition of Aspirin Resistance.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4018-4018
Author(s):  
Anna M. Dyszkiewicz-Korpanty ◽  
Anne Kim ◽  
James D. Burner ◽  
Eugene P. Frenkel ◽  
Ravindra Sarode
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Function ◽  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Blood Platelet ◽  
Aspirin Resistance ◽  
Impedance Aggregometry ◽  
Definition Of ◽  
Induced Aggregation

Abstract The reported incidence of aspirin (ASA) resistance ranges from 5 to 30%. Various platelet function assays have been employed to detect aspirin resistance in patients with cardio- and cerebrovascular disease. Such a high proposed incidence of ASA resistance poses a critical need for a rapid point-of -care (POC) platelet function test. Unfortunately, no uniformly accepted definition of ASA resistance exists. Platelet aggregation studies that have been used to define ASA resistance are time consuming and require special technical expertise. The Ultegra Rapid Platelet Function -ASA (RPFA-ASA) has been developed as a POC test that is performed without sample processing. This optical method measures agglutination of fibrinogen-coated beads upon platelet activation with arachidonic acid. In the presence of aspirin effect, however, the agglutination of the beads is inhibited. The described cutoff of ≥ 550 Aspirin Reaction Units (ARU) is termed non-responsiveness to ASA based on a preclinical study and subsequent correlation with epinephrine-induced platelet aggregation in platelet rich plasma. Since RPFA-ASA uses whole blood, we validated its performance characteristics against a classic whole blood platelet aggregation assay (WBA). We studied 50 healthy volunteers, aged 25–75 (24 men, 26 women) with normal CBC, who had not ingested anti-platelet drugs for 14 days prior to the study. Baseline studies included WBA (dual channel aggregometer, Chrono-log Inc., Havertown, PA) using both arachidonic acid (AA -0.5; 0.25 mM) and collagen (1; 2 μg/mL) as well as an RPFA-ASA assay (Accumetrics Inc., San Diego, CA). These studies were repeated after 3 days of ASA (325 mg/d) intake. Based on a review of the literature, we defined an adequate ASA response as a completely inhibited AA-induced platelet aggregation and at least 30% inhibition of collagen-induced aggregation (both concentrations of the agonist). Thus, those with < 30% inhibition of aggregation response to collagen were considered ASA resistant. Eleven subjects were ASA resistant by WBA (20%; 8 females and 3 males (aged 25–63). In contrast, since all 50 subjects achieved ARU values of < 550 ARU, none were recognized as an ASA non-responder by the RPFA-ASA. While the current cutoff of < 550 ARU posed by the Ultegra RPFA-ASA does identify those who have taken ASA, the assay is unable to recognize ASA non-responders. Thus, based on these data, the appropriate cutoff for the recognition of ASA resistance by the RPFA-ASA should be re-adjusted to a significantly lower level to ensure appropriate assay results.

scholarly journals Pharmacologic inhibition of thromboxane synthetase and platelet aggregation: modulatory role of cyclooxygenase products

Blood ◽  
1984 ◽  
Vol 63 (6) ◽  
pp. 1460-1466
Author(s):  
V Bertele ◽  
A Falanga ◽  
M Tomasiak ◽  
C Chiabrando ◽  
C Cerletti ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Normal Subjects ◽  
Gas Chromatography Mass Spectrometry ◽  
Thromboxane Synthetase ◽  
High Resolution Gas Chromatography ◽  
Pharmacologic Inhibition

Dazoxiben , an imidazole-derived selective inhibitor of thromboxane A2 (TxA2) synthetase, prevented TxB2 synthesis in vitro in platelet-rich plasma from 16 normal subjects. Inhibition of TxB2 synthesis was accompanied by increased generation of PGE2, PGF2 alpha, and PGD2, as shown by radioimmunoassay, thin-layer radiochromatography, and high- resolution gas chromatography-mass spectrometry. Even at dazoxiben concentrations (40–80 microM) above those inhibiting TxB2 synthesis, platelet aggregation induced by threshold concentrations of arachidonic acid was inhibited in only 4 of 16 subjects, referred to as responders. The remaining 12 individuals were defined as nonresponders. The aggregating effect of arachidonic acid and of the prostaglandin- endoperoxide analog U-46619 was potentiated by PGE2 and prevented by PGD2 at concentrations within the range of those detected in dazoxiben - treated platelet-rich plasma. The antiaggregating effect of dazoxiben was counteracted by PGE2 (in responders) and was potentiated by PGD2 (in nonresponders). Platelets from responders and nonresponders did not differ in the amount of immunoreactive PGE2 material or in their sensitivity to U-46619 or PGD2. It is concluded that inhibition of thromboxane synthetase does not per se prevent platelet aggregation. The functional result of thromboxane suppression appears to be modulated by an interplay of the prostaglandin-endoperoxides, PGE2 and PGD2, which are formed in excess.

scholarly journals Role of Cyclic Amp in Platelet Function : Evidence from Inhibition of Adenylate Cyclase in Intact Platelets by Adenosine Analogues

1977 ◽  
Author(s):  
R. J. Haslam ◽  
M. M. L. Davidson ◽  
J. V. Desjardins
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Platelet Function ◽  
Platelet Rich Plasma ◽  
Inhibitory Effects ◽  
Adenosine Analogues ◽  
Inhibitory Activities

Adenosine exerts independent stimulatory and inhibitory effects on the adenylate cyclase activity of platelet particulate fractions (Haslam & Lynham, 1972). Two adenosine analogues, 9-(tetrahydro-2-furyl) adenine (SQ 22536) and 2′, 5′-dideoxyadenosine (DDA) have now been found to show marked non-competitive inhibitory activities only. Basal and PGE1-stimulated adenylate cyclase activities were inhibited ~50% and ~70% respectively by 100 μM SQ 22536 and ~60% and ~80% respectively by 100 μM DDA. Both compounds also inhibited adenylate cyclase in intact platelets, when this was measured as the increase in cyclic [3H]AMP in platelets labelled with [3H] adenine and then incubated with papaverine. At the concentrations tested (10-500 μM), neither SQ 22536 nor DDA induced platelet aggregation or potentiated aggregation and release of [14C] 5-HT induced by suboptimal concentrations of ADP, Arg8-vasopressin, arachidonic acid or collagen added to heparinized or citrated platelet-rich plasma. However, both compounds partially blocked the inhibition by PGE1 or papaverine of aggregation induced by ADP or Arg8-vasopressin. From the concentrations exerting equal effects, DDA was ~3 times as potent in this regard as SQ 22536. Above 100 μM, the anti-inhibitory effects of both compounds decreased. The actions of these compounds in overcoming inhibition of aggregation by PGE1 were correlated with decreases in platelet cyclic [3H]AMP in platelets labelled with [3H] adenine. The results show that cyclic AMP plays no role in the responses of platelets to aggregating agents unless the platelet cyclic AMP level is elevated above the resting level and confirm that the effects of PGE1 on platelet function are mediated by cyclic AMP.

scholarly journals Pharmacologic inhibition of thromboxane synthetase and platelet aggregation: modulatory role of cyclooxygenase products

Blood ◽  
1984 ◽  
Vol 63 (6) ◽  
pp. 1460-1466 ◽  
Author(s):  
V Bertele ◽  
A Falanga ◽  
M Tomasiak ◽  
C Chiabrando ◽  
C Cerletti ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Normal Subjects ◽  
Gas Chromatography Mass Spectrometry ◽  
Thromboxane Synthetase ◽  
High Resolution Gas Chromatography ◽  
Pharmacologic Inhibition

Abstract Dazoxiben , an imidazole-derived selective inhibitor of thromboxane A2 (TxA2) synthetase, prevented TxB2 synthesis in vitro in platelet-rich plasma from 16 normal subjects. Inhibition of TxB2 synthesis was accompanied by increased generation of PGE2, PGF2 alpha, and PGD2, as shown by radioimmunoassay, thin-layer radiochromatography, and high- resolution gas chromatography-mass spectrometry. Even at dazoxiben concentrations (40–80 microM) above those inhibiting TxB2 synthesis, platelet aggregation induced by threshold concentrations of arachidonic acid was inhibited in only 4 of 16 subjects, referred to as responders. The remaining 12 individuals were defined as nonresponders. The aggregating effect of arachidonic acid and of the prostaglandin- endoperoxide analog U-46619 was potentiated by PGE2 and prevented by PGD2 at concentrations within the range of those detected in dazoxiben - treated platelet-rich plasma. The antiaggregating effect of dazoxiben was counteracted by PGE2 (in responders) and was potentiated by PGD2 (in nonresponders). Platelets from responders and nonresponders did not differ in the amount of immunoreactive PGE2 material or in their sensitivity to U-46619 or PGD2. It is concluded that inhibition of thromboxane synthetase does not per se prevent platelet aggregation. The functional result of thromboxane suppression appears to be modulated by an interplay of the prostaglandin-endoperoxides, PGE2 and PGD2, which are formed in excess.

Testosterone Potentiation of Ionophore and ADP Induced Platelet Aggregation : Relationship to Arachidonic Acid Metabolism

1981 ◽  
Vol 46 (02) ◽  
pp. 538-542 ◽  
Author(s):  
R Pilo ◽  
D Aharony ◽  
A Raz
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Unsaturated Fatty Acids ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Arachidonic Acid Metabolism ◽  
Ionophore A23187 ◽  
Low Concentrations ◽  
Induced Aggregation

SummaryThe role of arachidonic acid oxygenated products in human platelet aggregation induced by the ionophore A23187 was investigated. The ionophore produced an increased release of both saturated and unsaturated fatty acids and a concomitant increased formation of TxA2 and other arachidonate products. TxA2 (and possibly other cyclo oxygenase products) appears to have a significant role in ionophore-induced aggregation only when low concentrations (<1 μM) of the ionophore are employed.Testosterone added to rat or human platelet-rich plasma (PRP) was shown previously to potentiate platelet aggregation induced by ADP, adrenaline, collagen and arachidonic acid (1, 2). We show that testosterone also potentiates ionophore induced aggregation in washed platelets and in PRP. This potentiation was dose and time dependent and resulted from increased lipolysis and concomitant generation of TxA2 and other prostaglandin products. The testosterone potentiating effect was abolished by preincubation of the platelets with indomethacin.

Platelet Suruival and Function in Rats with Enhanced Thrombotic Tendency

1985 ◽  
Vol 54 (04) ◽  
pp. 739-743 ◽  
Author(s):  
Federica Delaini ◽  
Elisabetta Dejana ◽  
Ine Reyers ◽  
Elisa Vicenzi ◽  
Germana De Bellis Vitti ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Nephrotic Syndrome ◽  
Platelet Function ◽  
Laboratory Tests ◽  
Thrombus Formation ◽  
The Other ◽  
Mean Survival Time ◽  
The Mean ◽  
And Function ◽  
Thrombotic Tendency

SummaryWe have investigated the relevance of some laboratory tests of platelet function in predicting conditions of thrombotic tendency. For this purpose, we studied platelet survival, platelet aggregation in response to different stimuli, TxB2 and 6-keto-PGFlα production in serum of rats bearing a nephrotic syndrome induced by adriamycin. These animals show a heavy predisposition to the development of both arterial and venous thrombosis. The mean survival time was normal in nephrotic rats in comparison to controls. As to aggregation tests, a lower aggregating response was found in ADR-treated rats using ADP or collagen as stimulating agents. With arachidonic acid (AA) we observed similar aggregating responses at lower A A concentrations, whereas at higher AA concentrations a significantly lower response was found in nephrotic rats, despite their higher TxB2 production. Also TxB2 and 6-keto-PGFlα levels in serum of nephrotic rats were significantly higher than in controls. No consistent differences were found in PGI2-activity generated by vessels of control or nephrotic rats.These data show that platelet function may appear normal or even impaired in rats with a markedly increased thrombotic tendency. On the other hand, the significance of high TxB2 levels in connection with mechanisms leading to thrombus formation remains a controversial issue.

scholarly journals Inhaled NO inhibits platelet aggregation and elevates plasma but not intraplatelet cGMP in healthy human volunteers

2003 ◽  
Vol 285 (2) ◽  
pp. H637-H642 ◽  
Author(s):  
Maurice Beghetti ◽  
Catherine Sparling ◽  
Peter N. Cox ◽  
Derek Stephens ◽  
Ian Adatia
Keyword(s):  
Nitric Oxide ◽  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Function ◽  
Human Platelet ◽  
Healthy Human ◽  
Human Volunteers ◽  
Independent Mechanism ◽  
Inhaled No ◽  
Maximal Extent

Effects of inhaled nitric oxide (NO) on human platelet function are controversial. It is uncertain whether intraplatelet cGMP mediates the effect of inhaled NO on platelet function. We investigated the effect of 30 ppm inhaled NO on platelet aggregation and plasma and intraplatelet cGMP in 12 subjects. We performed platelet aggregation studies by using a photooptical aggregometer and five agonists (ADP, collagen, epinephrine, arachidonic acid, and ristocetin). During inhalation, the maximal extent of platelet aggregation decreased by 75% with epinephrine ( P < 0.005), 56% with collagen ( P < 0.005), and 20% with arachidonic acid ( P < 0.05). Responses to ADP (8% P > 0.05) and ristocetin (5% P > 0.05) were unaffected. Platelet aggregation velocity decreased by 64% with collagen ( P < 0.005), 60% with epinephrine ( P < 0.05), 33% with arachidonic acid ( P < 0.05), and 14% with ADP ( P > 0.05). Plasma cGMP levels increased from 2.58 ± 0.43 to 9.99 ± 5.57 pmol/ml ( P < 0.005), intraplatelet cGMP levels were unchanged (means ± SD: 1.96 ± 0.58 vs. 2.71 ± 1.67 pmol/109platelets; P > 0.05). Inhaled NO inhibits platelet aggregation via a cGMP independent mechanism.

Modulation of platelet function by reactive oxygen metabolites

1994 ◽  
Vol 267 (1) ◽  
pp. H308-H318 ◽  
Author(s):  
G. Ambrosio ◽  
P. Golino ◽  
I. Pascucci ◽  
M. Rosolowsky ◽  
W. B. Campbell ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Function ◽  
Guanylate Cyclase ◽  
Reactive Oxygen Metabolites ◽  
Cyclic Monophosphate ◽  
Cgmp Formation ◽  
Oxygen Metabolites ◽  
Exogenous H2o2

Reactive oxygen metabolites have been reported to affect platelet aggregation. However, this phenomenon is still poorly understood. In the present study we investigated the effects of superoxide radical and hydrogen peroxide (H2O2) on platelet function in vitro and correlated those effects to possible changes of platelet concentrations of cyclic nucleotides and thromboxane, since these systems play a key role in the response of platelets to activating stimuli. Human platelets were exposed to xanthine-xanthine oxidase (X-XO), a system that generates both superoxide radicals and H2O2. Sixty seconds of incubation with X-XO impaired aggregation in response to ADP (by 48%), collagen (by 71%), or the thromboxane mimetic U-46619 (by 50%). This effect was reversible and occurred in the absence of cell damage. Impairment of aggregation in platelets exposed to X-XO was due to H2O2 formation, since it was prevented by catalase but not by superoxide dismutase. Similarly, incubation with the pure H2O2 generator glucose-glucose oxidase also markedly inhibited ADP-induced platelet aggregation in a dose-dependent fashion. Impaired aggregation by H2O2 was accompanied by a > 10-fold increase in platelet concentrations of guanosine 3',5'-cyclic monophosphate (cGMP), whereas adenosine 3',5'-cyclic monophosphate levels remained unchanged. The inhibitory role of increased cGMP formation was confirmed by the finding that H2O2-induced impairment of platelet aggregation was largely abolished when guanylate cyclase activation was prevented by incubating platelets with the guanylate cyclase inhibitor, LY-83583. Different effects were observed when arachidonic acid was used to stimulate platelets. Exposure to a source of H2O2 did not affect aggregation to arachidonate. Furthermore, in the absence of exogenous H2O2, incubation with catalase, which had no effects on platelet response to ADP, collagen, or U-46619, virtually abolished platelet aggregation and markedly reduced thromboxane B2 production (to 44% of control) when arachidonic acid was used as a stimulus. In conclusion, our data demonstrate that H2O2 may exert complex effects on platelet function in vitro. Low levels of endogenous H2O2 seem to be required to promote thromboxane synthesis and aggregation in response to arachidonic acid. In contrast, exposure to larger (but not toxic) concentrations of exogenous H2O2 may inhibit aggregation to several agonists via stimulation of guanylate cyclase and increased cGMP formation.

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