Nucleoside triphosphates inhibit ADP, collagen, and epinephrine-induced platelet aggregation: role of P2Y₁ and P2Y₁₂ receptors.
BACKGROUND
Platelets express two ADP receptors namely P2Y1 and P2Y12 that regulate ADP and other agonists-induced platelet aggregation. P2Y1 receptor activation causes platelet shape change while P2Y12 receptor activation induces platelet aggregation. Previously, anti-aggregatory effects of ATP on ADP-induced and pro-aggregatory effects on epinephrine-induced platelet aggregation have been reported. However, the effects of other nucleoside triphosphates on platelet aggregation have never been described. The aim of the present study was to characterise the effects of nucleoside triphosphates (ATP, UTP, GTP, and CTP) on agonist-induced platelet aggregation.


METHODS
The experiments were performed on platelet rich plasma freshly isolated from blood donated by healthy human volunteers.


RESULTS
All the nucleoside triphosphates tested inhibited ADP- and collagen-induced platelet aggregation in a concentration-dependent manner with a rank order of potency, 2MeSATP >ATP ≥ α,β,methyleneATP>UTP >>CTP ≥ GTP. The IC50 values against ADP (10 μM)-induced platelet aggregation were 0.039 ± 0.013, 18 ± 7, 25 ± 6, 32 ± 9, 360 ± 130, and 400 ± 160 μM, respectively. Low concentrations of ATP induced platelet shape change which was due to contaminating ADP. However, higher concentrations antagonised ADP and MRS2365-induced platelet shape change. The ATP analogue α,β,methyleneATP and CTP but not UTP and GTP also antagonised ADP-induced platelet shape change. Similarly, low ATP concentrations potentiated epinephrine-induced platelet aggregation that was abolished by P2Y1 antagonist MRS2500 suggesting P2Y1 receptor activation due to contaminating ADP. Higher ATP concentrations, α,β,methyleneATP, UTP, CTP, and GTP antagonised epinephrine-induced platelet aggregation.


CONCLUSIONS
Thus, the data demonstrate nucleoside triphosphates in general act as P2Y12 receptor antagonists and antagonise ADP-, collagen-, and epinephrine-induced platelet aggregation.
Department of Cardiology/Angiology, University Hospital Giessen, Giessen, Germany. Electronic address: muhammad.aslam@med.uni-giessen.de.
Muhammad
M
Aslam
Daniel
D
Sedding
Ahmed
A
Koshty
Santot
S
Santoso
Rainer
R
Schulz
Christian
C
Hamm
Dursun
D
Gündüz
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001792:Blood Platelets / Q000166:cytology* / Q000378:metabolism*; D048430:Cell Shape; D003094:Collagen / Q000378:metabolism; D003570:Cytidine Triphosphate / Q000378:metabolism; D004837:Epinephrine / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D010974:Platelet Aggregation; D058472:Receptors, Purinergic P2Y1 / Q000378:metabolism*; D058925:Receptors, Purinergic P2Y12 / Q000378:metabolism*; D014544:Uridine Triphosphate / Q000378:metabolism
D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; D000244:Adenosine Diphosphate; D003570:Cytidine Triphosphate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D003094:Collagen; D014544:Uridine Triphosphate; D004837:Epinephrine
2-(Methylthio)adenosine 5′-diphosphate; 2-(Methylthio)adenosine 5′-triphosphate; 2MeSADP; 2MeSATP; ADP; ATP; CTP; Collagen; GTP; Nucleoside triphosphates; P2Y(12) receptors; Platelet aggregation; UTP; adenosine 5’ diphosphate; adenosine 5’ triphosphate; cytosine 5’ triphosphate; guanosine 5’ triphosphate; uridine 5’ triphosphate; α,β,m ATP; α,β-methylene ATP