Adenosine Diphosphate Platelet Aggregation Research Articles

The anti-platelet activity of panaxadiol fraction and panaxatriol fraction of Korean Red Ginseng in vitro and ex vivo

BackgroundThe anti-platelet activity of the saponin fraction of Korean Red Ginseng has been widely studied. The saponin fraction consists of the panaxadiol fraction (PDF) and panaxatriol fraction (PTF); however, their anti-platelet activity is yet to be compared. Our study aimed to investigate the potency of anti-platelet activity of PDF and PTF and to elucidate how well they retain their anti-platelet activity via different administration routes. MethodsFor ex vivo studies, Sprague-Dawley rats were orally administered 250 mg/kg PDF and PTF for 7 consecutive days before blood collection via cardiac puncture. Platelet aggregation was conducted after isolation of the washed platelets. For in vitro studies, washed platelets were obtained from Sprague-Dawley rats. Collagen and adenosine diphosphate (ADP) were used to induce platelet aggregation. Collagen was used as an agonist for assaying adenosine triphosphate release, thromboxane B2, serotonin, cyclic adenosine monophosphate, and cyclic guanosine monophosphate (cGMP) release. ResultsWhen treated ex vivo, PDF not only inhibited ADP and collagen-induced platelet aggregation, but also upregulated cGMP levels and reduced platelet adhesion to fibronectin. Furthermore, it also inhibited Akt phosphorylation induced by collagen treatment. Panaxadiol fraction did not exert any anti-platelet activity in vitro, whereas PTF exhibited potent anti-platelet activity, inhibiting ADP, collagen, and thrombin-induced platelet aggregation, but significantly elevated levels of cGMP. ConclusionOur study showed that in vitro and ex vivo PDF and PTF treatments exhibited different potency levels, indicating possible metabolic conversions of ginsenosides, which altered the content of ginsenosides capable of preventing platelet aggregation.

Impact of the PEAR1 polymorphism on clinical outcomes in Chinese patients receiving dual antiplatelet therapy after percutaneous coronary intervention.

Background: Patients might still experience major adverse cardiovascular events even with dual antiplatelet therapy after percutaneous coronary intervention. Our study aimed to explore the impact of gene polymorphism on clinical outcomes in one-year follow-up. Methods: A total of 171 patients treated with dual antiplatelet therapy afterpercutaneous coronary intervention from April to December 2020 in the first hospital of Jilin University enrolled in this study. Results: PEAR1 genetic polymorphisms was associated with the arachidonic acid(AA) and adenosine diphosphate(ADP) platelet aggregation. Hyperglycemia was associated with the rate of major adverse cardiovascular events. PEAR1GA+AA genetic genetic polymorphisms is associated with hyperglycemia. Conclusion:PEAR1 GG is a risk factor for AA and ADP platelet aggregation. Hyperglycemia can effect the one-year outcome. PEAR1 GA+AA genetic polymorphisms are associated with hyperglycemia.

Microvesicles generated following traumatic brain injury induce platelet dysfunction via adenosine diphosphate receptor.

Traumatic brain injury (TBI) can result in an acute coagulopathy including platelet dysfunction that can contribute to ongoing intracranial hemorrhage. Previous studies have shown adenosine diphosphate (ADP)-induced platelet aggregation to be reduced after TBI. In addition, circulating microvesicles (MVs) are increased following TBI and have been shown to play a role in post-TBI coagulopathy and platelet function. We hypothesized that post-TBI MVs would affect platelet aggregation in a murine head injury model. Moderate TBI was performed using a weight-drop method in male C57BL6 mice. Whole blood, plasma, MVs, and MV-poor plasma were isolated from blood collected 10 minutes following TBI and were mixed separately with whole blood from uninjured mice. Platelet aggregation was measured with Multiplate impedance platelet aggregometry in response to ADP. The ADP P2Y12 receptor inhibitor, R-138727, was incubated with plasma and MVs from TBI mice, and platelet inhibition was again measured. Whole blood taken from 10-minute post-TBI mice demonstrated diminished ADP-induced platelet aggregation compared with sham mice. When mixed with normal donor blood, post-TBI plasma and MVs induced diminished ADP-induced platelet aggregation compared with sham plasma and sham MVs. By contrast, the addition of post-TBI MV-poor plasma to normal blood did not change ADP-induced platelet aggregation. The observed dysfunction in post-TBI ADP platelet aggregation was prevented by the pretreatment of post-TBI plasma with R-138727. Treatment of post-TBI MVs with R-138727 resulted in similar findings of improved ADP-induced platelet aggregation compared with nontreated post-TBI MVs. Adenosine diphosphate-induced platelet aggregation is inhibited acutely following TBI in a murine model. This platelet inhibition is reproduced in normal blood by the introduction of post-TBI plasma and MVs. Furthermore, observed platelet dysfunction is prevented when post-TBI plasma and MVs are treated with an inhibitor of the P2Y12 ADP receptor. Clinically observed post-TBI platelet dysfunction may therefore be partially explained by the presence of the ADP P2Y12 receptor within post-TBI MVs. Level III.

Low Levels of High-Density Lipoprotein Cholesterol Are Linked to Impaired Clopidogrel-Mediated Platelet Inhibition.

Low high-density lipoprotein cholesterol (HDL-C) levels are an independent predictor of ischemic events in patients with atherosclerotic cardiovascular disease. This may in part be due to decreased clopidogrel-mediated platelet inhibition in patients with low HDL-C. We investigated the association of HDL-C with on-treatment platelet reactivity to adenosine diphosphate (ADP) in 314 patients on dual antiplatelet therapy with clopidogrel and aspirin undergoing angioplasty and stenting. Platelet P-selectin expression was assessed by flow cytometry, and platelet aggregation was determined by the VerifyNow P2Y12 assay and the Impact-R. High-density lipoprotein cholesterol levels were inversely associated with P-selectin expression and the VerifyNow P2Y12 assay (both P ≤ .01). Moreover, we found a positive correlation of HDL-C with surface coverage by the Impact-R ( P = .003). Patients with low HDL-C (≤35 mg/dL) exhibited a significantly higher P-selectin expression in response to ADP and higher platelet aggregation by the VerifyNow P2Y12 assay and the Impact-R than patients with normal HDL-C (>35 mg/dL; all P < .05). High on-treatment residual platelet reactivity by the VerifyNow P2Y12 assay occurred significantly more frequently in patients with low HDL-C levels than in those with normal HDL-C (47.4% vs 30.1%, P = .01). In conclusion, low HDL-C is linked to impaired clopidogrel-mediated platelet inhibition after angioplasty and stenting.

Beneficial effect of persimmon leaves and bioactive compounds on thrombosis

The effects of ethanol extracts of persimmon leaves (EPL) and the major flavonoids catechin, epicatechin, and epicatechin gallate on blood coagulation and platelet aggregation were evaluated. Anticoagulant activities were examined by monitoring the activated partial thromboplastin time (aPTT) and the prothrombin time (PT). EPL significantly prolonged PT and aPTT. The aPTT was significantly increased in the presence of catechin, epicatechin, and epicatechin gallate, compared with controls. In order to determine the antiplatelet activity, arachidonic acid (AA), collagen, and adenosine diphosphate (ADP)-induced platelet aggregation were examined. PL and the major flavonoids significantly reduced AA-induced platelet aggregation, although they did not significantly affect ADP and collagen-induced platelet aggregation, compared with controls. EPL and the major flavonoids significantly inhibited serotonin, thromboxane A2, and soluble P-selectin generation, compared with controls. PL has potential for prevention and improvement of thrombosis by inhibiting blood coagulation and platelet activation.

Inhibition of human platelet aggregation in vitro by standardized extract of Wendtia calycina

Wendtia calycina (Griseb.) Griseb., Vivianiaceae, is a Paraguayan herbaceous plant commonly known as burrito. Our previous study indicated that burrito leaves are a very good source of phenylpropanoid glycosides, principally verbascoside. From W. calycina leaves, a standardized, water-soluble extract rich in phenylpropanoid glycosides (WSE) has been developed on an industrial scale to be used as a food supplement, cosmetic, phytomedicine, and ingredient of different formulations. In this study, we investigated the effect of the WSE on human platelet aggregation in vitro induced by adenosine diphosphate (ADP), epinephrine (EPN), collagen (COL) or arachidonic acid (AA). WSE, concentration-dependently, inhibited ADP and EP-induced human platelet aggregation (IC50 were 0.82±0.15 mg/mL and 0.41±0.02 mg/mL, respectively). It did not inhibit collagen-induced platelet aggregation, thus suggesting a selectivity for the ADP-induced platelet activation pathways.

Efficacy of combination antiplatelet therapy and nicardipine for chronic cerebral infarction

To prevent recurrence of cerebral infarction (CI), the efficacy of antiplately therapy, when used in combination with a calcium antagonist, was examined. The study subjects were 57 chronic CI patients (40 men, 17 women; mean age, 68.5 years) who experienced either CI or its recurrence more than 3 months before the start of the study. They were randomly allocated into one of the following four groups for the 8-week study: group A—ticlopidine hydrochloride 200 mg once daily and nicardipine hydrochloride 20 mg three times daily (TID); group B—ticlopidine hydrochloride 200 mg once daily; group C—aspirin 81 mg once daily and nicardipine hydrochloride 20 mg TID; or group D—aspirin 81 mg once daily. Platelet aggregation was measured before treatment and 4 and 8 weeks after the initiation of each therapy by using adenosine diphosphate (ADP) (2 μM and 0.5 μM) and collagen (2 μg/mL), and evaluated in terms of percent maximum platelet aggregation. Results showed significant suppression of 2.0-μM ADP platelet aggregation in groups A, B, and C. At 0.5-μM ADP, only groups A and B showed significant platelet aggregation suppression. All groups showed significant suppression of collagen platelet aggregation. In comparing single therapy with combination therapy, groups A and B were not significantly different from one another after 4 or 8 weeks in 2-μM ADP or collagen platelet aggregation suppression. In contrast, group C had significantly greater suppression of both 2-μM ADP and collagen aggregations compared with group D. In conclusion, nicardipine hydrochloride administration with aspirin may be a useful alternative therapy for the prevention of CI recurrence.

Artificial Surface Effect on Red Blood Cells and Platelets in Laminar Shear Flow

Red blood cell (RBC) effects on platelet adhesion to a nonbiologic test surface (tetrafluoroethylene propylene copolymer) and platelet aggregation during laminar shear flow for shear rates to 5,680 s-1 (corresponding to shear stress to 200 dyne/cm2) were investigated. Results on hemoglobin (Hb) and adenosine diphosphate (ADP) release from RBCs, percent decrease of single platelets in the bulk, and percent of test surface covered with platelets were obtained in a cone-and-plate (CP) viscometer for samples of whole blood, suspensions of RBC ghosts in platelet-rich plasma (PRP), and suspensions of RBCs in either PRP or platelet-poor plasma. Results obtained over the shear rate range studied for samples of normal hematocrit indicated that low-stress shearing led to ADP and Hb release from intact RBCs; shear-induced release of ADP from RBCs was about twice that of platelets, and of the total ADP released, the ADP released from RBCs contributed about six times that of the platelets to single platelet reduction in the bulk and about twice that of the platelets to platelet adhesion, ie, coverage of the test surface with platelets. Results obtained for various hematocrits showed that above a threshold hematocrit of about 25% to 35% the RBCs (suspended in PRP) had a greater contribution to ADP release, platelet adhesion, and platelet aggregation than the platelets themselves. Single platelet reduction for samples of RBC ghosts suspended in PRP correlated with shear rate level and not with shear stress.

Artificial surface effect on red blood cells and platelets in laminar shear flow

Red blood cell (RBC) effects on platelet adhesion to a nonbiologic test surface (tetrafluoroethylene propylene copolymer) and platelet aggregation during laminar shear flow for shear rates to 5,680 s-1 (corresponding to shear stress to 200 dyne/cm2) were investigated. Results on hemoglobin (Hb) and adenosine diphosphate (ADP) release from RBCs, percent decrease of single platelets in the bulk, and percent of test surface covered with platelets were obtained in a cone-and-plate (CP) viscometer for samples of whole blood, suspensions of RBC ghosts in platelet-rich plasma (PRP), and suspensions of RBCs in either PRP or platelet-poor plasma. Results obtained over the shear rate range studied for samples of normal hematocrit indicated that low-stress shearing led to ADP and Hb release from intact RBCs; shear-induced release of ADP from RBCs was about twice that of platelets, and of the total ADP released, the ADP released from RBCs contributed about six times that of the platelets to single platelet reduction in the bulk and about twice that of the platelets to platelet adhesion, ie, coverage of the test surface with platelets. Results obtained for various hematocrits showed that above a threshold hematocrit of about 25% to 35% the RBCs (suspended in PRP) had a greater contribution to ADP release, platelet adhesion, and platelet aggregation than the platelets themselves. Single platelet reduction for samples of RBC ghosts suspended in PRP correlated with shear rate level and not with shear stress.

The influence of lithium and calcium ions on the aggregation of human blood platelets

Platelet aggregation in platelet-rich plasma, induced by adenosine diphosphate (ADP) collagen, thrombin, adrenalin and ristocetin, is inhibited by lithium ions. Calcium will enhance the aggregation induced by all these agents, except ristocetin. The aggregation of ristocetin-induced, formalin-fixed platelets is inhibited by lithium when the platelets are resuspended in saline or plasma. Lithium levels within the approved therapeutic range are sufficient to affect both ADP and ristocetin-induced platelet aggregation.