ユーグロブリン溶解時間と血漿中tPA, PAI濃度の関係

抄録

The relationship between tissue plasminogen activator (tPA), its fast acting inhibitor (PAI-1) and euglobulin clot lysis assay (ELT) were investigated with healthy volunteers' plasma.
New clot lysis assay method was utilized with a slight modification for ELT. Briefly, clot was made in a microtiter plate and turbidity of the clot was measured with 340nm by a microtiter plate reader periodically. The point of half lysis was determined as euglobulin lysis time 1/2 (Fig. 1). Duplicated samples were analyzed and the correlation coefficient (R) was 0.992 (p<0.001). TPA was assayed by EIA.
Total PAI (PAIt) and tPA-PAI complex (PAIc) were measured separately by the methods previously reported from this laboratory. Both tPA and PAI showed the significant correlation with ELT. TPA had a significantly positive, not negative, correlation with ELT (R=0.387, p<0.001). Higher correlation coefficients (R=0.580, p<0.001 and R=0.599, p<0.001) were obtained with PAIt and PAIf than with tPA and PAIc (R=0.427, p<0.001). The positive correlation was also obtained between tPA and PAI. PAIt and PAIc showed higher correlation coefficients (R=0.733, p<0.001 and R=0.827, p<0.001) with tPA than with PAIf (R=0.648, p<0.001). These data suggest that PAI can be released corresponding to the release of tPA and that the activity of tPA can be neutralized by PAI. That can be the reason why PAIt and PAIf were the more important factor to influence the ELT than tPA. We here show that PAI is highly important factor for ELT, especially, the amounts of free PAI being the key factor to determine the ELT, which can represent the potential activity of the fibrinolytic system.