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The tissue factor requirement in blood coagulation.
Thomas Orfeo1, Saulius Butenas, Kathleen E Brummel-Ziedins
1Department of Biochemistry, University of Vermont, Burlington, Vermont 05405, USA.
The Journal of Biological Chemistry
|October 11, 2005
Summary
Tissue factor (TF) initiates blood coagulation. Studies show TF is only essential during early phases; later stages become TF-independent, sustained by coagulation products, even with blood flow changes.
Area of Science:
- Biochemistry
- Hematology
Background:
- Thrombin generation is critical for hemostasis, involving initiation, propagation, and termination phases.
- A debate exists on whether sustained tissue factor (TF) is required for adequate procoagulant response.
Purpose of the Study:
- To investigate the necessity of TF during blood coagulation progression.
- To assess TF requirements during resupply conditions (flow replacement).
Main Methods:
- TF activity was eliminated at various time points during coagulation.
- Reactions were resupplied with fresh reactants without TF during the termination phase.
Main Results:
- Absolute TF dependence was observed for <10 seconds.
- A transitional period (10-240 s) showed decreasing TF dependence.
- TF independence was achieved after 240 seconds.
- Resupply experiments demonstrated TF-independent thrombin bursts.
Conclusions:
- The propagation phase marks the onset of TF independence.
- Coagulation products maintain prothrombin activation potential, ensuring TF independence.
- Transient, localized TF expression is sufficient for sustained coagulation under persistent flow.