Fibrinogenolysis and fibrinolysis in normal volunteers and patients with thrombosis after infusion of urokinase.

We have studied the effects of urokinase (UK) on concentration changes of alpha 2 antiplasmin (alpha 2 AP) and on fibrino(geno)lysis. Medium dose (480,000 u) or large dose (960,000 u) of UK was given to each of seven normal volunteers by intravenous drip infusion within six hours, and then blood and urine analyses were carried out. Total alpha 2 AP, which includes free alpha 2 AP and alpha 2 AP-plasmin complex, decreased to about 50% of the original value with large dose of UK. alpha 2 AP-plasmin complex appeared in the plasma one hr after UK infusion and increased up to 50% of total alpha 2 AP at the end of UK infusion. B beta peptides, which are liberated from fibrin(ogen) at the very early stage of fibrino(geno)lysis, increased significantly with UK infusion, and was 65 times as much as the normal range at the end of UK infusion. Urinary B beta peptides increased as well as plasma B beta peptides. On the other hand, fibrin(ogen) degradation products (FDP) measured with enzyme immunoassay (EIA) increased only slightly, and moreover, urinary FDP was not detectable at any time. Plasma fibrinogen levels did not decrease and changed within the normal range in both groups. We then gave 960,000 u of UK to four patients with deep vein thrombosis and blood analyses were carried out as with normal volunteers. The most significant observation different from that of normal volunteers was shown in FDP levels. Serum FDP levels of four patients increased significantly in comparison with normal volunteers. Urinary FDP increased as significantly as plasma FDP. In conclusion, the infusion of 960,000 u of UK caused only very early stage of fibrinogenolysis without advanced fibrinogenolysis in normal volunteers, but in thrombotic patients, advanced fibrinolysis was observed.