| Research Abstract |
Forty-three atherosclerotic rabbits undergoing balloon angioplasty of the iliac artery were randomized to either 7 day tPA infusion or a control group. The tPA group was divided into a high dose group(H)(2mg/kg/24h following 3mg/ kg/4h) and a low dose group(L)(0.6mg/kg/24h following 3mg/kg/4h). Balloon angioplasty (BA)(2.5mm balloon ; 3x60 sec, 10 atm inflations 60 sec apart) was performed 1 hour after tPA infusion. At 28 days after BA, areas of intima, media and adventitia were calculated at site of intimal hyperplasia. The cut face of the intima had an area of 0.07(〕SY.+-.〔)0.11mm^2 in the tPA(H) group and 0.11(〕SY.+-.〔)0.07mm^2 in the tPA(L) group, which were significantly smaller(p<0.01, p<0.05, respectively) than that in the control group (0.50(〕SY.+-.〔)0.25mm^2). The ratio of intimal to medial superficial content was significantly lower (p<0.05, respectively) in the tPA-treated group than in the control group (0.10(〕SY.+-.〔)0.13 ; tPA(H), 0.21(〕SY.+-.〔)0.19 ; tPA(L) vs 1.24(〕SY.+-.〔)0.73 ; control). In conclusion, seven-days tPA infusion prevented intimal hyperplasia in the injured vessel, suggesting that the removal of thrombus derived growth factor and the decrease of plasminogen activator inhibitor may inhibit smooth muscle cell proliferation.
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