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Activated protein C inhibits platelet prothrombin-converting activity.
Blood
|December 1, 1979
Summary
Activated protein C inhibits bovine platelet prothrombin conversion, a key clotting step. Factor Xa protects this activity, suggesting a regulatory role for activated protein C in blood coagulation.
Area of Science:
- Biochemistry
- Hematology
- Cell Biology
Background:
- Bovine platelets activated by thrombin enhance prothrombin to thrombin conversion.
- This conversion requires calcium ions and factor Xa.
- Activated protein C (APC), a vitamin K-dependent protein, regulates coagulation.
Purpose of the Study:
- To investigate the inhibitory effect of APC on platelet prothrombin-converting activity.
- To determine the role of factor Xa in this inhibition.
- To elucidate the mechanism by which APC regulates platelet-mediated clotting.
Main Methods:
- Assessing prothrombin to thrombin conversion in activated bovine platelets.
- Incubating platelets with APC and factor Xa over time.
- Measuring factor Xa receptor site availability on platelets.
Main Results:
- APC significantly inhibits platelet prothrombin-converting activity in a time-dependent manner.
- Factor Xa partially protects platelet activity from APC inactivation but does not reverse inhibition.
- APC treatment leads to a concurrent reduction in factor Xa receptor sites and prothrombin-converting activity.
Conclusions:
- APC effectively inactivates platelet prothrombin-converting activity.
- APC's mechanism involves the loss of factor Xa receptor sites on platelets.
- APC plays a crucial role in regulating blood coagulation by modulating platelet activity.