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The effect of some epsilon-aminocaproic acid derivatives on platelet responses

100%

Bruzgo I., Tomasiak M., Stelmach H., Midura-Nowaczek K.

Acta Biochimica Polonica

2004

tom 51

nr 1

ε-Aminocaproic acid (EACA) is a synthetic low molecular drug with antifibrinolytic activity. However, treatment with this drug can be incidentally associated with an increased thrombotic tendency. The aim of the present work was to test synthetic EACA derivatives for their antiplatelet activities. We investigated the effect of three EACA derivatives with antifibrinolytic activity: I. ε-aminocaproyl-L-leucine hydrochloride (HCl*H-EACA-L-Leu-OH), II. ε-aminocaproyl-L-(S-benzyl)-cysteine hydrochloride (HCl*H-EACA-L-Cys(S-Bzl)-OH) and III. ε-aminocaproyl-L-norleucine (H-EACA-L-Nle-OH) on platelet responses (aggregation and adhesion) and on their integrity. It was found that: 1. as judged by LDH release test, none of the tested compounds, up to 20 mM, was toxic to platelets, 2. in comparison with EACA, all the synthetic derivatives inhibited much stronger the ADP- and collagen-induced aggregation of platelets suspended in plasma (platelet rich plasma) and aggregation of these cells in whole blood, 3. EACA and its derivatives exerted a similar inhibitory effect on the thrombin-induced adhesion of platelets to fibrinogen-coated surfaces. Since platelet activation and blood coagulation are tightly associated processes, the antiplatelet properties of EACA derivatives are expected to indicate reduced throm- botic properties of these derivatives compared to EACA.

Adenosine diphosphate receptors on blood platelets - potential new targets for antiplatelet therapy

100%

Rozalski M., Nocun M., Watala C.

Acta Biochimica Polonica

2005

tom 52

nr 2

Platelets play a key role not only in physiological haemostasis, but also under pathological conditions such as thrombosis. Platelet activation may be initiated by a variety of agonists including thrombin, collagen, thromboxane or adenosine diphosphate (ADP). Although ADP is regarded as a weak agonist of blood platelets, it remains an important mediator of platelet activation evoked by other agonists, which induce massive ADP release from dense granules, where it occurs in molar concentrations. Thus, ADP action underlies a positive feedback that facilitates further platelet aggregation and leads to platelet plug formation. Additionally, ADP acts synergistically to other, even weak, agonists such as serotonin, adrenaline or chemokines. Blood platelets express two types of P2Y ADP receptors: P2Y1 and P2Y12. ADP-dependent platelet aggregation is initiated by the P2Y1 receptor, whereas P2Y12 receptor augments the activating signal and promotes platelet release reaction. Stimulation of P2Y12 is also essential for ADP-mediated complete activation of GPIIb-IIIa and GPIa-IIa, and further stabilization of platelet aggregates. The crucial role in blood platelet biology makes P2Y12 an ideal candidate for pharmacological approaches for anti-platelet therapy.

Ograniczanie wyników

2 Acta Biochimica Polonica

1 Bruzgo I.

1 Midura-Nowaczek K.

1 Nocun M.

1 Rozalski M.

1 Stelmach H.

1 Tomasiak M.

1 Watala C.

1 2005

1 2004

Wyniki wyszukiwania

The effect of some epsilon-aminocaproic acid derivatives on platelet responses

Adenosine diphosphate receptors on blood platelets - potential new targets for antiplatelet therapy