title: D-Phe-Pro-Arg-chloromethylketone: its potential use in inhibiting the formation of in vitro artifacts in blood collected during tissue-type plasminogen activator thrombolytic therapy.
abstract: In vitro artifacts due to proteolysis may occur in blood samples containing recombinant tissue-type plasminogen activator (rt-PA) due to continued activation of plasminogen to plasmin by rt-PA. The aim of this study was to identify a rapid inhibitor of rt-PA that would not interfere in assays designed to monitor thrombolytic events. When rt-PA was added at 5 micrograms/ml to whole blood and incubated at 25 degrees C, fibrinogen decreased 50 percent, plasminogen levels decreased 90 percent and alpha 2-antiplasmin decreased below detectable levels. If D-Phe-Pro-Arg-chloromethylketone (PPACK) or aprotinin were added before the addition of rt-PA there was no significant loss of fibrinogen. Only PPACK completely inhibited changes in fibrin degradation products, plasminogen and alpha 2-antiplasmin. PPACK was also found to inhibit the binding of rt-PA to plasma protease inhibitors in vitro. Rhesus monkeys were infused with rt-PA and blood samples were taken with either PPACK or aprotinin in the collection syringe. There was a significant increase in the recovery of immunoreactive rt-PA and consistent measures of fibrinogen, FDPs, plasminogen, and alpha 2-antiplasmin in the PPACK group as compared to the aprotinin group which indicates that PPACK will prevent the in vitro formation of artifacts due to the presence of active rt-PA.
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology* / Q000627:therapeutic use; D007611:Aprotinin / Q000494:pharmacology; D001800:Blood Specimen Collection; D004789:Enzyme Activation; D005340:Fibrinogen / Q000378:metabolism; D005341:Fibrinolysin / Q000378:metabolism; D005343:Fibrinolytic Agents; D006801:Humans; D007700:Kinetics; D010958:Plasminogen / Q000378:metabolism; D011994:Recombinant Proteins / Q000627:therapeutic use*; D013917:Thrombin / Q000037:antagonists & inhibitors*; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D005343:Fibrinolytic Agents; D011994:Recombinant Proteins; D005340:Fibrinogen; D010958:Plasminogen; D007611:Aprotinin; D013917:Thrombin; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin; C040308:phenylalanyl-prolyl-arginine-chloromethyl ketone