Rabbit factor V: different effects of thrombin and venom, a source of error in assay

Publisher Website
Google Scholar
Abstract
Factor V was measured by one-stage techniques utilizing tissue thromboplastin and Russell viper venom on test samples of rabbit ear and heart blood prepared as diluted hemolyzed whole blood and as undiluted plasma. The assay with venom proved unreliable in the rabbit. It badly underestimates rabbit factor V activity relative to human factor V activity. Moreover, it grossly overestimates factor V activity in rabbit plasma treated with small amounts of thrombin or thought to contain traces of thrombin from its mode of collection, when such samples are compared with a standard rabbit plasma. Both of these discrepancies probably reflect the inability of rabbit factor V (in contrast to human factor V) to increase in reactivity on incubation with viper venom. Fresh (but not stored), diluted, hemolyzed ear blood samples assayed by the tissue thromboplastin technique proved satisfactory for serial factor V determinations in the rabbit with minimal blood loss.