Physical exercise induces enhancement of urokinase-type plasminogen activator (u-PA) levels in plasma.

The enhancement of the blood fibrinolytic potential by physical exercise is generally attributed to the release of tissue-type plasminogen activator (t-PA) from the vessel wall. In this study we have investigated the possible contribution of urokinase-type plasminogen activator (u-PA). Six healthy male volunteers (age 21-25 years) were screened for their ability to perform maximal exercise for their age-group for 12 min on a bicycle ergometer. Subsequently, on one occasion they were required to remain supine for 2 h (from 8.30 a.m. onwards) an on another they performed maximal exercise (from 9.00 a.m. onwards). During exercise an increase in u-PA antigen and plasmin-activatable pro-urokinase (proUK) activity, concurrent with t-PA antigen and euglobulin t-PA activity, was observed in all six volunteers, while at rest these parameters remained unaffected. Mean u-PA- and t-PA antigen increased, respectively, from 4.2 +/- 1.0 ng/ml and 5.8 +/- 2.1 ng/ml before exercise to 9.8 +/- 3.0 ng/ml and 18.3 +/- 3.8 ng/ml (peak). Mean plasmin-activatable proUK activity and t-PA activity increased, respectively, from 2.1 +/- 0.4 ng/ml and 0.3 +/- 0.2 ng/ml before exercise to 4.3 +/- 1.7 ng/ml and 7.2 +/- 4.0 ng/ml (peak). The increases were statistically significant throughout (paired t-test, pre vs post, antigen P less than 0.005 and activity P less than 0.02). After cessation of exercise u-PA and t-PA declined concurrently to normal values with a 50% decay in about 5 min.(ABSTRACT TRUNCATED AT 250 WORDS)