H Matsuno1, O Kozawa, M Niwa, T Uematsu. 1. Department of Pharmacology, Gifu University School of Medicine, Japan. leuven@cc.gifu-u.ac.jp
Abstract
BACKGROUND: Aurintricarboxylic acid (ATA) prevents von Willebrand factor binding to platelet glycoprotein (GP) Ib, with higher-molecular-weight ATA more effective than the lower-molecular-weight compound. We investigated the effects of high-molecular-weight ATA (Mr=7500), obtained by fractionating commercial ATA, in the injured hamster carotid artery. METHODS AND RESULTS: Platelet aggregation was induced in vitro with ADP (2.5 micromol/L) or botrocetin (5 microg/mL) in hamster platelet-rich plasma. IC50 values were 348.6+/-22.4 and 8.2+/-3.2 microg/mL, respectively. The endothelium of hamster carotid artery was denuded with a modified catheter. Continuous administration of high-molecular-weight ATA (10, 30, and 100 microg x kg(-1) x h(-1)) with an infusion pump produced antithrombotic effects in a dose-dependent manner, as evaluated by prolongation of time to occlusion. Neointima formation was observed 2 weeks after catheterization, and proliferating smooth muscle cells (SMCs) were identified by the thymidine analogue 5-bromo-2-deoxyuridine (BrdU). Continuous treatment with the compound (100 microg x kg(-1) x h(-1)) with a 2ML1 Alzet infusion pump resulted in a reduction of neointimal area by 38.0+/-8.8% and decreased the BrdU index on days 1 and 7 significantly. DNA synthesis in DDT1MF2 hamster SMCs was also decreased by the compound in a dose-dependent manner. In histological observation, the process of endothelial healing was improved by this treatment with the compound. CONCLUSIONS: Inhibition of platelet adhesion by von Willebrand factor binding to platelet GP Ib by high-molecular-weight ATA results in the prevention of thrombus formation and the suppression of neointima lesion. In addition, high-molecular-weight ATA has an inhibitory effect on SMC proliferation. This inhibition of both platelet adhesion and SMC proliferation markedly reduced vascular stenosis.
BACKGROUND:Aurintricarboxylic acid (ATA) prevents von Willebrand factor binding to platelet glycoprotein (GP) Ib, with higher-molecular-weight ATA more effective than the lower-molecular-weight compound. We investigated the effects of high-molecular-weight ATA (Mr=7500), obtained by fractionating commercial ATA, in the injured hamster carotid artery. METHODS AND RESULTS: Platelet aggregation was induced in vitro with ADP (2.5 micromol/L) or botrocetin (5 microg/mL) in hamster platelet-rich plasma. IC50 values were 348.6+/-22.4 and 8.2+/-3.2 microg/mL, respectively. The endothelium of hamster carotid artery was denuded with a modified catheter. Continuous administration of high-molecular-weight ATA (10, 30, and 100 microg x kg(-1) x h(-1)) with an infusion pump produced antithrombotic effects in a dose-dependent manner, as evaluated by prolongation of time to occlusion. Neointima formation was observed 2 weeks after catheterization, and proliferating smooth muscle cells (SMCs) were identified by the thymidine analogue 5-bromo-2-deoxyuridine (BrdU). Continuous treatment with the compound (100 microg x kg(-1) x h(-1)) with a 2ML1 Alzet infusion pump resulted in a reduction of neointimal area by 38.0+/-8.8% and decreased the BrdU index on days 1 and 7 significantly. DNA synthesis in DDT1MF2 hamster SMCs was also decreased by the compound in a dose-dependent manner. In histological observation, the process of endothelial healing was improved by this treatment with the compound. CONCLUSIONS: Inhibition of platelet adhesion by von Willebrand factor binding to platelet GP Ib by high-molecular-weight ATA results in the prevention of thrombus formation and the suppression of neointima lesion. In addition, high-molecular-weight ATA has an inhibitory effect on SMC proliferation. This inhibition of both platelet adhesion and SMC proliferation markedly reduced vascular stenosis.