Inhibition of Fibrinolytic Activity In-Vivo by Dexamethasone Is Counterbalanced by an Inhibition of Platelet Aggregation

1992 ◽  
Vol 68 (01) ◽  
pp. 069-073 ◽  
Author(s):  
J J J van Giezen ◽  
J W C M Jansen
Keyword(s):  
Platelet Aggregation ◽  
Fibrinolytic Activity ◽  
Ex Vivo ◽  
Dose Range ◽  
Coagulation System ◽  
Loop Model ◽  
Prothrombotic State ◽  
Inhibition Of Platelet Aggregation ◽  
Pai 1

SummaryDexamethasone decreases the fibrinolytic activity in cultured medium of several cell types by an induction of PAI-1 synthesis. As a result of this enhanced PAI-1 synthesis a prothrombotic state is expected in patients treated with dexamethasone. However, such a prothrombotic state is not reported as a major adverse effect. We have studied the effects of dexamethasone (dose range: 0.1–3.0 mg/kg) on the fibrinolytic system of rats after a 5 day pretreatment period. It appeared that dexamethasone dose dependently decreased the fibrinolytic activity (a dose of 1 mg/kg showed a reduction of about 40%). This reduced fibrinolytic activity could be functionally translated into an increased thrombus size as measured with a venous thrombosis model: thrombus size was increased by 50% with 1 mg/kg dexamethasone. No effects could be measured on the coagulation system, but it appeared that ex-vivo measured platelet aggregation was dose dependently inhibited by dexamethasone treatment. This effect resulted in-vivo in prolonged obstruction times as measured with a modified aorta-loop model. These results indicate that the expected prothrombotic state due to a diminished fibrinolytic activity caused by dexamethasone is counterbalanced by an inhibition of platelet aggregation.

The Antithrombotic Effect of Borneol Related to Its Anticoagulant Property

2008 ◽  
Vol 36 (04) ◽  
pp. 719-727 ◽  
Author(s):  
Yan-Hong Li ◽  
Xiao-Ping Sun ◽  
Yin-Qing Zhang ◽  
Ning-Sheng Wang
Keyword(s):  
Platelet Aggregation ◽  
Fibrinolytic Activity ◽  
Ex Vivo ◽  
Anticoagulant Activity ◽  
Thrombin Time ◽  
Inhibitory Effects ◽  
Antithrombotic Activity ◽  
Coagulation Parameters ◽  
Venous Shunt

Borneol is consumed excessively in China and Southeast Asian countries particularly in combined formula for preventing cardiovascular disease, but few studies were conducted on its effects on thrombosis. In this study, the antithrombotic and antiplatelet activities of borneol were investigated on thrombosis in vivo and on platelet aggregation ex-vivo. In addition, the coagulation parameters and influence on fibrinolytic activity were also assessed. The results showed that borneol had concentration dependent inhibitory effects on arterio-venous shunt and venous thrombosis but no effect on ADP and AA-induced platelet aggregation. Meanwhile, borneol prolonged the coagulation parameters for prothrombin time (PT) and thrombin time (TT), but did not show any fibrinolytic activity. It suggested that the antithrombotic activity of borneol and its action in combined formula for preventing cardiovascular diseases might be due to anticoagulant activity rather than antiplatelet activity.

Biochemical and Pharmacologic Profiling of a Novel Dual Acting Antithrombin Agent with Antiprotease and Antiplatelet Actions. Hematologic Implications.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1876-1876
Author(s):  
Jawed Fareed ◽  
D. Hoppensteadt ◽  
W. Haque ◽  
J. Diakur ◽  
W. Jeske ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Dose Range ◽  
Coagulation System ◽  
Antithrombotic Drugs ◽  
Platelet Activity ◽  
Titration Assay ◽  
Sites Of Action ◽  
Dose Dependent

Abstract Background: The pathogenesis of thrombosis involves both cellular and humoral processes. Most antithrombotic drugs exhibit either anti-protease or anti-platelet effects. A combination of anti-protease and anti-platelet drugs provides better efficacy in the management of thrombotic disorders. A series of synthetic low molecular weight serine protease inhibitors with varying anti-platelet effects (Medicure Inc.) are being assessed for antithrombotic properties. Materials and Methods: This investigation reports on a compound with low antithrombin/high anti-platelet activity MC 45301 (A) and a compound with high antithrombin/low anti-platelet activity MC 45308 (B) activity in in-vitro and in-vivo settings used to profile antithrombotic drugs. Results: A exhibited strong anti-platelet actions as measured using ADP as an agonist (IC50=1.1 g/ml), whereas B had a higher IC50 (9.4 g/ml). In the antithrombin titration assay A (>100 μg/ml) showed a relatively higher IC50 than B (45 μg/ml). In the global anticoagulant assays, A exhibited somewhat weaker effects than B. In the Xa generation assay, both compounds exhibited similar effects. However, in the thrombin generation assays B exhibited stronger effects. In whole blood assays both compounds produced anticoagulant and anti-platelet effects. Intravenous administration of these compounds to rabbits over a dose range of 50–500 g/kg produced strong dose dependent antithrombotic actions. In comparison to direct antithrombin agents such as argatroban, at a comparable dose, B produced identical antithrombotic actions, which were disproportional to the systemic anticoagulant effects. A produced modest antithrombotic actions with minimal ex vivo clotting effects. This data is highly suggestive that compounds with dual targets are able to produce stronger antithrombotic actions relative to monotherapeutic agents. Additional studies in arterial thrombosis may provide newer insights into the antithrombotic actions of compounds with dual sites of action. Moreover, these agents may be more effective in thrombotic conditions where both platelets and the coagulation system are involved.

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

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 ◽  
Inhibition Of Platelet Aggregation ◽  
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.

Retinoic Acid Enhances Fibrinolytic Activity In-Vivo by Enhancing Tissue Type Plasminogen Activator (t-PA) Activity and Inhibits Venous Thrombosis

1993 ◽  
Vol 69 (04) ◽  
pp. 381-386 ◽  
Author(s):  
J J J van Giezen ◽  
G d I A Boon ◽  
J W C M Jansen ◽  
B N Bouma
Keyword(s):  
Retinoic Acid ◽  
Platelet Aggregation ◽  
Venous Thrombosis ◽  
Fibrinolytic Activity ◽  
Ex Vivo ◽  
Tissue Type ◽  
Clot Lysis ◽  
Thrombin Time ◽  
Tissue Extracts

SummaryWe studied the profibrinolytic effect and the anti-thrombotic potential of retinoic acid in-vivo. Male Wistar rats were treated with retinoic acid either acutely or twice daily for a period of 5 consecutive days in a dose range of 0.01 to 3.0 mg/kg. Fibrinolytic activity was measured ex-vivo using the diluted blood clot lysis test and net t-PA activity in tissue extracts was measured in a spectrophotometric rate assay. Clot lysis was dose dependently increased by retinoic acid up to about 170% (relative to vehicle treated rats) at a dose of 3 mg/kg. No tachyphylaxis could be detected. Ex-vivo measured fibrinolytic activity after single administration of 1 mg/kg of retinoic acid peaked at 3 h after ingestion. Even after 18 h a significantly higher clot lysis rate was measured. Lysis of blood clots from vehicle and retinoic acid treated rats could be completely blocked by addition of tranexamic acid or antibodies against rat t-PA before clot formation. t-PA activity in plasma was slightly increased after retinoic acid treatment; no effects were measured on plasma PAI-1, u-PA, plasminogen, and α2-antiplasmin levels. t-PA activity in lung and kidney was marginally enhanced by retinoic acid but in heart and aortic tissue extracts t-PA activity was increased by about 50%. We confirmed this potential anti-thrombotic property in an in-vivo venous thrombosis model. A reduced clot size was observed after retinoic acid administration (35% reduction at a dose of 1 mg/kg). We could not detect any effect on ex-vivo measured platelet aggregation, bleeding time, prothrombin time, thrombin time, partial thromboplastin time or plasma fibrinogen level, indicating that there were no effects on platelet aggregation or blood coagulation. We conclude that retinoic acid enhanced fibrinolytic activity in-vivo by selectively enhancing t-PA activity and that retinoic acid is a potential anti-thrombotic agent in-vivo.

Antithrombotic Effects and Bleeding Time Prolongation with Synthetic Platelet GPIIb/llla Inhibitors in Animal Models of Platelet-Mediated Thrombosis

1994 ◽  
Vol 71 (01) ◽  
pp. 095-102 ◽  
Author(s):  
Désiré Collen ◽  
Hua Rong Lu ◽  
Jean-Marie Stassen ◽  
Ingrid Vreys ◽  
Tsunehiro Yasuda ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Bleeding Time ◽  
Bolus Injection ◽  
Cell Injury ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Femoral Vein ◽  
Thrombotic Occlusion ◽  
Antithrombotic Effects

SummaryCyclic Arg-Gly-Asp (RGD) containing synthetic peptides such as L-cysteine, N-(mercaptoacetyl)-D-tyrosyl-L-arginylglycyl-L-a-aspartyl-cyclic (1→5)-sulfide, 5-oxide (G4120) and acetyl-L-cysteinyl-L-asparaginyl-L-prolyl-L-arginyl-glycyl-L-α-aspartyl-[0-methyltyrosyl]-L-arginyl-L-cysteinamide, cyclic 1→9-sulfide (TP9201) bind with high affinity to the platelet GPIIb/IIIa receptor.The relationship between antithrombotic effect, ex vivo platelet aggregation and bleeding time prolongation with both agents was studied in hamsters with a standardized femoral vein endothelial cell injury predisposing to platelet-rich mural thrombosis, and in dogs with a carotid arterial eversion graft inserted in the femoral artery. Intravenous administration of G4120 in hamsters inhibited in vivo thrombus formation with a 50% inhibitory bolus dose (ID50) of approximately 20 μg/kg, ex vivo ADP-induccd platelet aggregation with ID50 of 10 μg/kg, and bolus injection of 1 mg/kg prolonged the bleeding time from 38 ± 9 to 1,100 ± 330 s. Administration of TP9201 in hamsters inhibited in vivo thrombus formation with ID50 of 30 μg/kg, ex vivo platelet aggregation with an ID50 of 50 μg/kg and bolus injection of 1 mg/kg did not prolong the template bleeding time. In the dog eversion graft model, infusion of 100 μg/kg of G4120 over 60 min did not fully inhibit platelet-mediated thrombotic occlusion but was associated with inhibition of ADP-induccd ex vivo platelet aggregation and with prolongation of the template bleeding time from 1.3 ± 0.4 to 12 ± 2 min. Infusion of 300 μg/kg of TP9201 over 60 min completely prevented thrombotic occlusion, inhibited ex vivo platelet aggregation, but was not associated with prolongation of the template bleeding time.TP9201, unlike G4120, inhibits in vivo platelet-mediated thrombus formation without associated prolongation of the template bleeding time.

A Comparative Ex Vivo Study of Plasminogen Activators and Proteases for Fibrinolytic Activity and Side Effects in Rabbits

1977 ◽  
Vol 37 (01) ◽  
pp. 154-161 ◽  
Author(s):  
B. A Janik ◽  
S. E Papaioannou
Keyword(s):  
Side Effects ◽  
Effective Dose ◽  
Fibrinolytic Activity ◽  
Ex Vivo ◽  
Plasminogen Activators ◽  
Assay System ◽  
Coagulation Parameters ◽  
Ex Vivo Assay

SummaryUrokinase, streptokinase, Brinase, trypsin, and SN 687, a bacterial exoprotease, have been evaluated in an ex vivo assay system. These enzymes were injected into rabbits and the fibrinolytic activity as well as other coagulation parameters were measured by in vitro techniques. Dose-response correlations have been made using the euglobulin lysis time as a measure of fibrinolytic activity and the 50% effective dose has been determined for each enzyme. Loading doses, equal to four times the 50% effective dose, were administered to monitor potential toxicity revealing that Brinase, trypsin, and SN 687 were very toxic at this concentration.Having established the 50% effective dose for each enzyme, further testing was conducted where relevant fibrinolytic and coagulation parameters were measured for up to two days following a 50% effective dose bolus injection of each enzyme. Our results have demonstrated that urokinase and streptokinase are plasminogen activators specifically activating the rabbit fibrinolytic system while Brinase, trypsin and SN 687 increase the general proteolytic activity in vivo.The advantages of this ex vivo assay system for evaluating relative fibrinolytic potencies and side effects for plasminogen activators and fibrinolytic proteases have been discussed.

Ex Vivo Inhibition of Platelet Aggregation in Patients with Severe Limb Arteriopathy Treated with BAY U3405, a Specific IX A2 Receptor Antagonist

1994 ◽  
Vol 72 (05) ◽  
pp. 659-662 ◽  
Author(s):  
S Bellucci ◽  
W Kedra ◽  
H Groussin ◽  
N Jaillet ◽  
P Molho-Sabatier ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Ex Vivo ◽  
Randomized Study ◽  
In Vivo Studies ◽  
Walking Distance ◽  
Peripheral Blood Flow ◽  
Walking Ability ◽  
Double Blind ◽  
Platelet Factor

SummaryA double-blind, placebo-controlled randomized study with BAY U3405, a specific thromboxane A2 (TX A2) receptor blocker, was performed in patients suffering from severe stade II limb arteriopathy. BAY U3405 or placebo was administered in 16 patients at 20 mg four times a day (from day 1 to day 3). Hemostatic studies were done before therapy, and on day 2 and day 3 under therapy. On day 3, BAY U3405 was shown to induce a highly statistically significant decrease of the velocity and the intensity of the aggregations mediated by arachidonic acid (56 ± 37% for the velocity, 58 ± 26% for the intensity) or by U46619 endoperoxide analogue (36 ± 35% for the velocity, 37 ± 27% for the intensity). Similar results were already observed on day 2. By contrast, such a decrease was not noticed with ADP mediated platelet aggregation. Furthermore, plasma levels of betathrombo-globulin and platelet factor 4 remained unchanged. Peripheral hemodynamic parameters were also studied. The peripheral blood flow was measured using a Doppler ultrasound; the pain free walking distance and the total walking ability distance were determined under standardized conditions on a treadmill. These last two parameters show a trend to improvement which nevertheless was not statistically significant. All together these results encourage further in vivo studies using BAY U3405 or related compounds on a long-term administration.

scholarly journals ROLE OF NITRIC OXIDE (NO) IN CAPSAICIN MEDIATED ANTI-PLATELET ACTIVITY IN IN VITRO, IN VIVO, EX-VIVO MODEL OF PLATELET AGGREGATION ASSAY AND ARTERIAL THROMBOSIS IN RAT: POTENTIAL THERAPEUTIC TARGET?

2018 ◽  
Vol 10 (4) ◽  
pp. 44
Author(s):  
Mihir K Patel ◽  
Kiranj K. Chaudagar ◽  
Anita A. Mehta
Keyword(s):  
Platelet Aggregation ◽  
Arterial Thrombosis ◽  
Ex Vivo ◽  
Platelet Activity ◽  
Aggregation Assay ◽  
Thrombosis Model ◽  
Platelet Aggregation Assay

Objective: Although recent advances in the treatment of congestive heart disease, mortality among patients’ remains a questionable remark. Therefore, we evaluated the role of capsaicin on in vitro and ex vivo platelet aggregation induced by Adenosine Di-Phosphate (ADP) as well as in in vivo thrombosis models and role of NO, KATP was also identified in the capsaicin-induced anti-platelet animal model as well as in vivo model of arterial thrombosis.Methods: According to body weight wistar rats were divided into five groups. Group I and Group II was treated with saline and capsaicin (3 mg/kg, i. v), while animals from Group III were treated with N(ω)-nitro-L-arginine methyl ester (L-NAME) (30 mg/kg, i. v) 30 min before administration of capsaicin (3 mg/kg, i. v). Group IV animals were treated with glibenclamide (10 mg/kg,i. v) 30 min before administration of capsaicin (3 mg/kg, i. v). Group V was considered as a positive control and administered clopidogrel (30 mg/kg, p. o). Animals were subjected for in vitro, ex-vivo platelet aggregation assay. ADP (30µM) was utilized as an aggregating agent in these experiments. After these assays; animals of each group were subjected for subaqueous tail bleeding time in a rat model and FeCl3-induced arterial thrombosis model in rats.Results: In ADP-induced in vitro platelet aggregation, a significant reduction in % platelet aggregation was observed at 50µM (64.35±4.641) and 100µM (52.72±4.192) concentration of capsaicin as compared to vehicle control (85.82±3.716). Capsaicin (3 mg/kg, i. v) also showed a significant reduction (49.53±4.075) in ex-vivo ADP-induced platelet aggregation as compared to vehicle control (89.38±2.057). In FeCl3 induced arterial thrombosis model, Capsaicin (3 mg/kg, i. v) exhibited an increase in time to occlusion in this rodent model and presence of the L-NAME and glibenclamide had inhibited the activity of capsaicin.Conclusion: In our study, capsaicin (50 µM, 100µM) exhibited potent anti-platelet activity in ADP-induced platelet aggregation, similarly capsaicin exhibited significant anti-platelet action in the ex-vivo study. Moreover, the presence of L-NAME and glibenclamide inhibited the anti-thrombotic and anti-platelet action of capsaicin. Therefore, it was concluded that NO and KATP may be involved in the anti-thrombotic action of capsaicin.

Comparison of the effect of coagulation and platelet function impairments on various mouse bleeding models

2014 ◽  
Vol 112 (08) ◽  
pp. 412-418 ◽  
Author(s):  
Nima Vaezzadeh ◽  
Ran Ni ◽  
Paul Y. Kim ◽  
Jeffrey I. Weitz ◽  
Peter L. Gross
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Saphenous Vein ◽  
Ex Vivo ◽  
Arterial Injury ◽  
Inhibitory Antibody ◽  
Study Objective ◽  
Tail Tip

SummaryHaemostatic impairments are studied in vivo using one of several murine bleeding models. However it is not known whether these models are equally appropriate for assessing coagulation or platelet function defects. It was our study objective to assess the performance of arterial, venous and combined arterial and venous murine bleeding models towards impaired coagulation or platelet function. Unfractionated heparin (UFH) or αIIbβ3 inhibitory antibody (Leo.H4) were administered to mice, and their effects on bleeding in saphenous vein, artery, and tail tip transection models were quantified and correlated with their effects on plasma clotting and ADP-induced platelet aggregation, respectively. All models exhibited similar sensitivity with UFH (EC50 dose = 0.19, 0.13 and 0.07 U/g, respectively) (95% CI = 0.14 – 0.27, 0.08 – 0.20, and 0.03 – 0.16 U/g, respectively). Maximal inhibition of ex vivo plasma clotting could be achieved with UFH doses as low as 0.03 U/g. In contrast, the saphenous vein bleeding model was less sensitive to αIIbβ3 inhibition (EC50 = 6.9 µg/ml) than tail transection or saphenous artery bleeding models (EC50 = 0.12 and 0.37 µg/ml, respectively) (95% CI = 2.4 – 20, 0.05 – 0.33, and 0.06 – 2.2 µg/ml, respectively). The EC50 of Leo.H4 for ADP-induced platelet aggregation in vitro (8.0 µg/ml) was at least 20-fold higher than that of the tail and arterial, but not the venous bleeding model. In conclusion, venous, arterial and tail bleeding models are similarly affected by impaired coagulation, while platelet function defects have a greater influence in models incorporating arterial injury.

scholarly journals Protease-Activated Receptors 1 and 3 are Differentially Expressed on Human Monocyte Subsets and are Upregulated by Lipopolysaccharide Ex Vivo and In Vivo

2019 ◽  
Vol 119 (09) ◽  
pp. 1394-1402 ◽  
Author(s):  
Barbara Thaler ◽  
Philipp J. Hohensinner ◽  
Johanna Baumgartner ◽  
Patrick Haider ◽  
Konstantin A. Krychtiuk ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Critical Role ◽  
Human Monocyte ◽  
In Vivo Model ◽  
Monocyte Subsets ◽  
Plasminogen Activator Inhibitor 1 ◽  
Protease Activated Receptors ◽  
Messenger Ribonucleic Acid ◽  
Pai 1

AbstractMonocytes are activated in inflammatory conditions via a variety of cytokine receptors as well as in a procoagulatory setting through thrombin, acting upon protease-activated receptors (PARs). This study investigated the expression pattern of PAR1 and PAR3 on human monocyte subsets. Furthermore, a possible regulation of the expression of PAR1 and PAR3 in these cells by inflammatory activation were studied. CD16+ monocytes showed significantly higher levels of PAR1 and PAR3 as compared with CD16− monocytes. Ex vivo treatment of whole blood with lipopolysaccharide (LPS) increased PAR1 and PAR3 messenger ribonucleic acid (mRNA) in human monocytes. In addition, increase of PAR1 was seen in all three subsets upon LPS treatment, whereas PAR3 increased significantly only in CD16− monocytes and nonclassical CD16+ monocytes. Protein levels of PAR1 and PAR3 significantly increased on monocytes in vivo in human endotoxemia 1 hour after LPS infusion. PAR1 increased significantly in CD16− monocytes and nonclassical CD16+ monocytes. In this in vivo model, PAR3 was also significantly elevated in CD16− monocytes and increased slightly albeit not significantly in CD16+ monocytes. Endotoxemia increased plasminogen activator inhibitor-1 (PAI-1) and tissue factor (TF) expression in monocytes in humans. Pretreatment of healthy volunteers with the PAR1 antagonist vorapaxar blocked the increase in PAI-1 but not the increase in TF. We here provide new evidence for a critical role for monocytes as cellular mediators that contribute to the activation of coagulation in diseases characterized by an inflammatory state.

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