Thrombosis and haemostasis vol:82 issue:5 pages:1510-1515
Two immunoassays for the specific quantitation of rabbit plasminogen activator inhibitor-1 (PAI-1) antigen and activity in biological samples were developed and applied for the evaluation of PAI-1 in rabbits. Levels of PAI-1 antigen in rabbit plasma were 9.8 +/- 3.6 ng/ml (mean +/- SD, n = 6), with a corresponding value of 20.5 +/- 13.5 ng/ml for PAI-1 activity. In rabbit serum PAI-1 antigen was 11.8 +/- 4.9 ng/ml (n = 6) and PAI-1 activity was 2.9 +/- 2.0 ng/ml (n = 6). Endotoxin injection (20 mu g/kg, iv) induced a time-dependent increase of both PAI-1 antigen and PAI-1 activity levels in rabbit plasma, eventually resulting in a 40- to 90-fold increase (p < 0.0001 vs baseline). A linear correlation was found between PAI-1 antigen and activity levels in normal plasma (r = 0.90, n = 6. p < 0.05) and in plasma from endotoxin-treated rabbits (r = 0.98, n = 20, p < 0.001). Analysis of PAI-1 antigen and activity in lysates of washed rabbit platelets revealed the absence of PAI-1 (i.e. < 0.03 ng/10(8) platelets).