An association between the factor VII coagulant activity and thrombin activity induced by surface/cold exposure of normal human plasma.
To test whether factor VII activation correlated with the generation of thrombin activity when plasma was exposed to a glass surface and reduced temperature, an association was sought between the changes in factor VII clotting activity (VIIc) and fibrinopeptide A concentration (an index of thrombin activity) in platelet-poor citrated plasma from 42 healthy adults. The Spearman rank correlation (rs) between responses was 0.82 (P less than 0.001). The VIIc assay response to surface/cold exposure was unaffected when thrombin was suppressed by hirudin. An assay for factor VII activity based upon its activation of tritiated factor X revealed an association between the increase in fibrinopeptide A concentration and reduction in functional factor VII concentration during activation of a subset of 22 plasma samples (rs = -0.62; P = 0.003). This loss of functional factor VII was probably due to conversion of active factor VII to its non-functional end-product by factor Xa. The results suggest that VIIc is an index of flux within the coagulation system and support the hypothesis that a high VIIc is an indicator of a hypercoagulable state.
D000328:Adult; D001777:Blood Coagulation; D003080:Cold Temperature; D005167:Factor VII / Q000378:metabolism*; D015942:Factor VIIa; D005260:Female; D005344:Fibrinopeptide A / Q000032:analysis; D005898:Glass; D006629:Hirudins / Q000494:pharmacology; D006801:Humans; D008297:Male; D013048:Specimen Handling / Q000295:instrumentation; D013917:Thrombin / Q000378:metabolism*
D006629:Hirudins; D005344:Fibrinopeptide A; D005167:Factor VII; D015942:Factor VIIa; D013917:Thrombin