Thromb Haemost 1979; 42(03): 885-894
DOI: 10.1055/s-0038-1666937
Original Article
Schattauer GmbH Stuttgart

Studies on Metabolism of Urokinase and Mechanism of Thrombolysis by Urokinase

Tatsuo Ueno
The Third Department of Internal Medicine, Gunma University School of Medicine, Maebashi, Gunma, Japan
,
Norio Kobayashi
The Third Department of Internal Medicine, Gunma University School of Medicine, Maebashi, Gunma, Japan
,
Tadashi Maekawa
The Third Department of Internal Medicine, Gunma University School of Medicine, Maebashi, Gunma, Japan
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Publikationsverlauf

Received 10. November 1978

Accepted 13. Februar 1979

Publikationsdatum:
23. August 2018 (online)

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Summary

Pharmacokinetics of intravenously injected 125I-labeled urokinase (125I-UK) of a molecular weight of 33,000 daltons in normal rabbits and patients with various diseases were investigated. The plasma clearance of 125I-UK in rabbits was described by a biexponential curve within six hours with a half-life of 8 minutes, 2.3 hours, respectively. The radioactivity in the liver and kidneys 15 minutes after iv injection with 125I-UK was 9.6% and 14.0% of the radioactivity injected, respectively. Approximately 80% of the total radioactive material injected was excreted in the urine in 18 hours. No increase in activator activity in the urine was observed after a large amount of UK injection. Activity uptake of 125I-UK by experimentally induced arterial thrombus was little. Lysis of the stasis thrombus was produced by injecting 7.5 × 104 IU of UK in only one out of 8 rabbits. In vitro contact experiment revealed that transfer of 125I-UK to plasma clot is slow (24 hours for 10% of 125I-UK by plasma clot). In 4 patients plasma clearance of 125I-UK was essentially similar to that in rabbits. From the results obtained optimal dosage regimen of UK administration for complete thrombolysis in vivo was discussed.