title: Effect of fibrinopeptides A and B on human and rat platelet aggregation in vitro.
abstract: The effect of fibrinopeptides on platelet aggregation is reported. Fibrinopeptide A (minimal effective concentration, 0.65 microM) aggregated human (but not rat) platelets suspended in plasma and at lower concentrations (0.01-0.1 microM) potentiated platelet aggregation due to ADP and collagen in both species. Fibrinogen mimicked these effects of fibrinopeptide A. P-bromophenacyl bromide (100 microM), mepacrine (10 microM), indomethacin (10 microM) and dazoxiben (10 microM) inhibited human platelet aggregation induced by fibrinopeptide A and fibrinogen. In both species, fibrinopeptide B (0.65-6.5 microM) antagonised the platelet inhibitory effect of PGI2 and PGD2 but not adenosine. Antagonism was non-competitive in nature. The concentration of fibrinopeptide A required to potentiate platelet aggregation occurs naturally in the plasma of patients with thrombotic disease suggesting this effect may be of physiological significance during the formation of a thrombus. The novel action of fibrinopeptide B to reduce the platelet inhibitory effect of PGI2 and PGD2 may also contribute to the control of thrombus formation.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D003094:Collagen / Q000494:pharmacology; D011464:Epoprostenol / Q000494:pharmacology; D005340:Fibrinogen / Q000494:pharmacology*; D005344:Fibrinopeptide A / Q000494:pharmacology*; D005345:Fibrinopeptide B / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects*; D015230:Prostaglandin D2 / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D005344:Fibrinopeptide A; D005345:Fibrinopeptide B; D000244:Adenosine Diphosphate; D005340:Fibrinogen; D003094:Collagen; D011464:Epoprostenol; D015230:Prostaglandin D2