Fibrinogen plays an integral part in ADP-induced platelet aggregation. Controversy
exists in regard to the role of the carboxy termini of fibrinogen Aa chains in this
reaction. We have attempted to clarify this problem in view of the availability of
a highly purified FII fibrinogen fraction. Kabi fibrinogen or its purified fractions
FI, FII and FIII-IV-V were added to washed platelets in the presence of Tyrode-HEPES
buffer pH 7.4. Aggregation was initiated by the addition of calcium and ADP. These
fibrinogen fractions equally promoted ADP-induced platelet aggregation. The major
difference among these fractions is in their Aα chains. The FI fraction contains intact
Aα chains while FII and FIH-IV-V fractions have one and two partially degraded Aα
chains at the carboxy terminal portion respectively. We conclude that the carboxy
terminal portion of the Aα chain does not play an important role in promoting ADP-induced
platelet aggregation.
Keywords
Fibrinogen - Platelet aggregation - Fibrinogen fractions