Platelet GPIIb/IIIa receptor inhibition by SC-49992 prevents thrombosis and rethrombosis in the canine carotid artery.
OBJECTIVE
Platelet glycoprotein IIb/IIIa (GPIIb/IIIa) receptors represent the final common pathway for aggregation. GPIIb/IIIa inhibition with antibodies or RGD peptides prevents arterial thrombosis. The present study examined the ability of SC-49992 (SC), a GPIIb/IIIa receptor antagonist, to prevent thrombosis in a canine model of carotid artery thrombosis.


METHODS
Both carotid arteries of anaesthetised dogs were instrumented with Doppler probes. A 300 microA current was applied to the intimal surface of the right carotid artery via an intraluminal electrode; time to occlusive thrombus formation was noted. SC (30 and 60 micrograms/.kg-1 x min-1, intravenously) or saline was infused for 240 min. The procedure for thrombus formation was repeated after 60 min of drug infusion for the left carotid artery.


RESULTS
SC did not alter heart rate or blood pressure. Frequency of occlusive thrombus formation was reduced or prevented in a dose dependent manner (control = 100%, n = 12; SC 30 micrograms = 50%, n = 6; SC 60 micrograms = 0%, n = 6; p < 0.05). SC resulted in a reduction in thrombus weight (p < 0.05) v control. Ex vivo platelet aggregation to ADP and arachidonic acid was inhibited. Platelet reactivity remained inhibited 60 min after cessation of SC infusion. In a second group of animals, a carotid artery thrombus was formed and lysed with administration of anisoylated plasminogen streptokinase activator complex (0.05 U.kg-1). SC (60 micrograms.kg-1 x min-1, intravenously, n = 6) or saline (n = 6) was infused for 240 min. In dogs receiving saline there was an 83% rate of rethrombosis; none of the SC treated animals had reocclusion after recanalisation (p < 0.05).


CONCLUSIONS
SC-49992 inhibits ex vivo platelet aggregation, prevents occlusive thrombus formation in a canine model of arterial thrombosis, and prevents rethrombosis after thrombolysis. The data are consistent with results obtained with murine monoclonal antibodies directed against the platelet GPIIb/IIIa receptor.
Department of Pharmacology, University of Michigan Medical School, Ann Arbor 48109-0626.
W E
WE
Rote
S W
SW
Werns
J H
JH
Davis
L P
LP
Feigen
K S
KS
Kilgore
B R
BR
Lucchesi
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002341:Carotid Artery Thrombosis / Q000517:prevention & control*; D004151:Dipeptides / Q000627:therapeutic use*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D019038:Platelet Glycoprotein GPIb-IX Complex; D010980:Platelet Membrane Glycoproteins; D011971:Receptors, Immunologic / Q000187:drug effects; D012008:Recurrence
C074050:8-guanidino-octanoyl-Asp-Phe; D004151:Dipeptides; D010975:Platelet Aggregation Inhibitors; D019038:Platelet Glycoprotein GPIb-IX Complex; D010980:Platelet Membrane Glycoproteins; D011971:Receptors, Immunologic; C032193:glycoprotein receptor GPIb-IX