• K Deguchi, S Murashima, M Nishikawa, and S Shirakawa.
• College of Medical Science, Mie University.
• Nippon Rinsho. 1992 Feb 1;50(2):297-302.

AbstractThe aim of this study is to evaluate the relationship between tissue plasminogen activator (tPA)/PA inhibitor (PAI) complex and PAI, and platelet in the circulating blood. tPA/PAI complex and active PAI (act PAI; Teijin Co., Japan), and PAI antigen (PAI ant; Biopool AB, Sweden) were assayed by enzyme immunoassay (EIA). The mean concentrations (ng/10(9) platelets) in supernatant from lysate of platelet rich plasma (PRP) and washed platelets were 27.1 +/- 9.2, 1.5 +/- 1.2 in tPA/PAI complex, 188.7 +/- 46.1, 83.3 +/- 7.5 in act PAI and 236.2 +/- 41.6, 191.9 +/- 45.1 in PAI ant, respectively. PRP was mixed with ADP (10(-5), 10(-4), 10(-3) M), for 3 min and the supernatant after centrifugation then was provided for assay of PAI and tPA/PAI complex. Concentrations of act PAI, PAI ant and tPA/PAI complex dose-dependently increased with ADP. Almost the same results were obtained, when collagen and other agents were used instead of ADP. This study revealed that platelets contained quantities PAI (as free PAI) and released PAI during aggregation, and that a part of the PAI immediately formed a complex with tPA. Those findings suggested that platelets may play an important role on the formation of thrombus, in the way of anti-fibrinolysis, in addition to novel platelet functions, such as aggregation.

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