Measurement of fibrinopeptide a in canine blood—An interim report

Measurement of canine fibrinopeptide A (cFPA) by radioimmunoassay is a sensitive and specific index of thrombin action in vivo . Accuracy and reproducibility of the assay procedure on measurements in samples of canine plasma has been improved by use of a simplified processing procedure. Levels of cFPA immunoreactivity in normal, anaesthetized mongrel dogs are 2. 4 ± 0.4 pmols/ml. This baseline cFPA level cannot be further reduced by short-term heparinization using dosages of heparin (200 U/kg) sufficient to prolong the APTT to at least 1 1 2 times control value. The removal of elevated levels of homologous cFPA from the plasma compartment of anaesthetized, heparinized dogs can be approximated by a double exponential decay curve. Initial fall in cFPA levels is rapid ( T 1 2 = 4. 0 ± 0. 3 min ), but lengthens as the levels approach the normal range. The applicability of the cFPA to studies of experimentally induced intravascular coagulation is demonstrated.