The nature of interactions between tissue-type plasminogen activator and platelets

Journal Article · Sun Jul 15 04:00:00 EDT 1990 · Thrombosis Research; (USA)

DOI:https://doi.org/10.1016/0049-3848(90)90131-U· OSTI ID:6322920

Torr, S R; Winters, K J; Santoro, S A; Sobel, B E ^[1]

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1. Washington Univ., St. Louis, MO (USA)

To elucidate interactions responsible for inhibition of aggregation of platelets in platelet-rich plasma (PRP) harvested from whole blood preincubated with t-PA, experiments were performed with PRP and washed platelets under diverse conditions of preincubation. Both ADP and collagen induced aggregation were inhibited in PRP unless aprotinin had been added to the preincubated whole blood concomitantly with t-PA. However, in washed platelets prepared after the same exposure aggregation was intact. When washed platelets were supplemented with fibrinogen degradation products (FDPs) in concentrations simulating those in whole blood preincubated with t-PA, aggregation induced with either ADP or collagen was inhibited. Thus, the inhibition in PRP depended on generation of FDPs by activated plasminogen. The functional integrity of surface glycoprotein (GP) IIb/IIIa receptors in washed platelets was documented by autoradiography after SDS-PAGE of surface labeled GPs and by fibrinogen binding despite preincubation of the whole blood or washed platelets themselves with t-PA and plasminogen as long as exogenous calcium (greater than or equal to 0.1 microM) was present. In contrast, when calcium was absent, the platelet GP IIb/IIIa receptor was rendered susceptible to degradation by plasmin, and aggregation was inhibited by preincubation at 37 degrees C even if aprotinin was present when aggregation was being assayed. These observations reconcile disparate results in the literature from studies in vivo and in vitro by demonstrating that inhibition of aggregation of platelets in PRP and in whole blood reflects indirect effects of plasminogen activation rather than direct effects of t-PA or plasmin on the platelets themselves.

• OSTI ID: 6322920
• Journal Information: Thrombosis Research; (USA), Journal Name: Thrombosis Research; (USA) Vol. 59:2; ISSN THBRA; ISSN 0049-3848
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ADP
AUTORADIOGRAPHY
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BLOOD COAGULATION
BLOOD COAGULATION FACTORS
BLOOD PLATELETS
BODY FLUIDS
COAGULANTS
COLLAGEN
DRUGS
FIBRINOGEN
FIBRINOLYTIC AGENTS
GLOBULINS
GLYCOPROTEINS
HEMATOLOGIC AGENTS
HEMOSTATICS
INHIBITION
IODINE ISOTOPES
ISOTOPES
KINETICS
MATERIALS
MEMBRANE PROTEINS
NUCLEOTIDES
ORGANIC COMPOUNDS
PLASMINOGEN
PROTEINS
REACTION KINETICS
RECEPTORS
SCLEROPROTEINS