Summary
Automated human plasma, continuous monitoring of the formation and inactivation of
thrombin during the coagulation process provides an adequate way to detect hypo- and
hypercoagulant conditions. Here, we describe an analogous procedure to determine the
endogenous thrombin potential (ETP), i. e. the free thrombin concentration-time integral,
of coagulating rat plasma. When activated with tissue factor, the ETP of plasma from
Wistar rats was comparable to the ETP of human plasma, in spite of a relatively short
half-life time of free thrombin in rat plasma. The ETP was highly sensitive to heparin
as well as to administration of vitamin K antagonist or feeding of the animals with
a vitamin K-deficient diet. In plasma that was activated under sub-optimal conditions
(reduced levels of tissue factor or vitamin K-dependent coagulation factors), the
ETP increased with the rate of thrombin formation in the first minutes of the coagulation
process. Since both parameters are dependent of the prothrombin concentration, it
appears that this level plays an important role in determining both the initial and
total activity of the coagulation system. Thus, automated measurement of free thrombin
during the coagulation process of rat plasma allows a detailed analysis of hypocoagulability
in this animal model.
Key words
Endogenous thrombin potential - hypocoagulability - rat - tissue factor - vitamin
K
