Aurin tricarboxylic acid inhibits platelet adhesion to collagen by binding to the 509-695 disulphide loop of von Willebrand factor and competing with glycoprotein Ib.
Aurin tricarboxylic acid (ATA) is known to inhibit ristocetin-induced platelet agglutination but not arachidonic acid-, epinephrine- or ADP-induced aggregation. Its capacity to abolish human von Willebrand factor (vWF)-platelet interactions was further investigated by measurement of platelet adhesion to collagen, platelet agglutination tests and binding studies. In flowing blood using parallel-plate perfusion chambers and human collagen, ATA inhibited platelet adhesion to completion in a dose-dependent manner only at the highest shear rate tested (2,600 s-1). It was without effect at 100 and 650 s-1. ATA completely abolished vWF-dependent platelet agglutination induced by ristocetin, botrocetin and asialo-vWF, respectively. 125I-vWF binding to ristocetin- and botrocetin-treated platelets, to heparin and to sulfatides as well as 125I-botrocetin binding to vWF was competitively inhibited by ATA. By contrast, binding of 125I-vWF to collagen was not affected. To further localize the domain of vWF interacting with ATA, experiments of inhibition of binding of selected 125I-monoclonal antibodies (MoAbs) to immobilized vWF by ATA were performed. Our data led to the conclusion that: 1) the interaction of ATA with vWF involves sequences of the A1 disulphide loop of vWF (residues 509-695) and close epitopes which interact with GPIb and 2) the inhibition of platelet adhesion by ATA occurs only at a high shear rate where vWF is known to play a key role. Thus ATA, which blocks the vWF/GPIb pathway by interfering with vWF and not with platelets, is a potential tool in preventing the early stages of thrombosis.
Girma
J P
JP
Inserm U.143, Hôpital de Bicêtre, Paris, France.
Fressinaud
E
E
Christophe
O
O
Rouault
C
C
Obert
B
B
Takahashi
Y
Y
Meyer
D
D
D001312:Aurintricarboxylic Acid / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites / Q000502:physiology; D001667:Binding, Competitive / Q000502:physiology; D003094:Collagen / Q000097:blood*; D003435:Crotalid Venoms / Q000037:antagonists & inhibitors; D004220:Disulfides / Q000097:blood*; D006385:Hemagglutination Inhibition Tests; D006388:Hemagglutinins / Q000187:drug effects; D006801:Humans; D010973:Platelet Adhesiveness / Q000187:drug effects*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D011485:Protein Binding; D012310:Ristocetin / Q000037:antagonists & inhibitors; D013314:Stress, Mechanical; D014841:von Willebrand Factor / Q000187:drug effects* / Q000378:metabolism
D003435:Crotalid Venoms; D004220:Disulfides; D006388:Hemagglutinins; D010980:Platelet Membrane Glycoproteins; D014841:von Willebrand Factor; D012310:Ristocetin; D001312:Aurintricarboxylic Acid; C030961:botrocetin; D003094:Collagen