THE DETERMINATION OF FUNCTIONAL PLASMINOGEN-ACTIVATOR INHIBITORS (PAI) BASED ON THE INHIBITION OF UROKINASE - PAI NORMAL RANGE AND CIRCADIAN VARIATIONS IN HEALTHY DONORS - COMPARISON WITH OTHER METHODS

For a newly developed assay for plasminogen activator inhibitor (PAI) activity, a reference range has been established with 266 plasmas from healthy volunteers. The highly asymmetric distribution has a median of 1.1 urokinase-inhibiting u/ml, with the 90% percentile at 3.5 u/ml. PAI activities in men were significantly higher than in women (p<0.0002). The new assay, which is based on the inhibition of urokinase by PAI, correlates well with previously described methods for PAI determination which exploit the inhibition of tissue-type plasminogen activator (t-PA). In 5 volunteers, circadian variations of PAI have been demonstrated with peak activity at night and early in the morning. Also, there is a significant correlation of PAI activity with relative body mass. © 1990 Longman Group UK Ltd.