| Objective: To investigate the effects of tea polyphenols on proliferation of vascular smooth muscle cells(VSMs) and collagen in the arterial media, and its relationship with the changes of tissue-type plasminogen activator ( tPA ) and angiotensin II(Agll). Then to evaluate its probability to prevent vascular restenosis after percutaneous transluminal coronary angioplasty in clinic.Methods: 30 male New Zealand White rabbits, weighted from 2.3 to 2.7 kg, were divided randomly as the control group ( n=10 ), the low dose tea polyphenols group ( n=10 , 100mg/kg.day ) and the high dose tea polyphenols group( n=10 , 800mg/kg.day ). With a reference to Chen SJ's method, 2.5mm coronary balloon was used to denude the intima of the right common carotid artery, 0.lIU/kg heparin was used as anticoagulants. The rabbits were fed with standard food after operation for 4 weeks. In the two drug groups , tea polyphenols was poured into the stomach after dissolved in the saline. In the control group, the same amount of saline was poured into the stomach. Water was not limited. The plasm level of tPA and Agll were detected by enzyme-linked immunosorbent assay and radio-immunosorbent assay respectively before the injury and 3,7,11,14,22,28 days after the injury . The animals were killed and carotid arteries were removed at the end of 4 weeks .With HE staining , masson's staining and computer analysis of pathological graph , we calculated the collagen content in media ( collagen area in media /media area , the unit is percentage ), and vascular smooth muscle cells count (the number of VSMs in unit area in media, the unit is I/ kum2 ). Data were analized by SPSS 10.0 software, data were expressed as mean+SD,data were analyzed by one-factor ANOVA to determine significance between groups. Significance was estabalished at P0.05, most significance was established at P0.01.Results: Most rabbits were healthy during the test, penicillin were injected to all rabbits for three days after operation. As time went by, four rabbits died ( two in the control group, one in the low dose tea polyphenols group, one in the high tea polyohenols group ). Twenty-six rabbits were alive at the end of the test ( eight in the control group, nine in the low dose tea polyphenols group, nine in the high dose tea polyphenols group ).The plasma level of tissue-type plasminogen activator increased in all three groups. The one in the high dose tea polyphenols was ( 0.1691+0.0672 ) IU/L, Before operation, 3 days, 7 days, 11 days, 14 days, 22 days, 28 days, the level of tPA were 0.0818 IU/L, 0.1242 IU/L, 0.1800 IU/L, 0.1634IU/L, 0.2372 IU/L, 0.2291 IU/L, 0.1773 IU/L, respectively; The one in the low dose tea polyphenols was ( 0.1406+0.0427 ) IU/L, Before operation, 3 days, 7 days, 11 days, 14 days, 22 days, 28 days, the level of tPA were 0.0777 IU/L, 0.1242 IU/L, 0.1343 IU/L, 0.1550 IU/L, 0.1292 IU/L, 0.1700 IU/L, 0.2004 IU/L, respectively; The one in the control group was ( 0.1263+0.041 ) IU/L, Before operation, 3 days, 7 days, 11 days, 14 days, 22 days, 28 days, the level of tPA were 0.0771 IU/L, 0.0949 IU/L, 0.1094 IU/L, 0.1530 IU/L, 0.1235 IU/L, 0.1594 IU/L, 0.1801 IU/L, respectively. In four weeks after operation, plasma tPA level increased gradually in three groups, at end of the fourth week, the tPA level was still higher than the one before operation. The plasma tPA level in the high dose tea polyphenols group was higher than the one in the control group, the difference was most significant ( P<0.001 ). The plasma tPA level in the high dose tea polyphenols group was higher than the one in the low dose tea polyphenols group, the difference was significant ( PO.05 ).The plasma level of angiotensin II increased obviously in all three groups. The angiotensin II level in the high dose tea polyphenols was ( 1229.256+283.394 ) pg/ml, Before operation, 3 days, 7 days, 11 days, 14 days, 22 days, 28 days, the level of angiotensin II were 907.140 pg/ml, 1247.958 pg/ml, 1304.458 pg/ml, 909.726 pg/ml, 1209.736 pg/ml, 1446.692 pg/ml, 1614.952 pg/ml, respe...
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