Defective platelet aggregation induced by platelet activating factor in myeloproliferative disorders: deficiency of an aspirin-independent mechanism?
Platelets from 6 out of 10 patients with myeloproliferative disorders showed only a single reversible wave of aggregation when challenged with platelet activating factor (PAF). Preexposure to subthreshold concentrations of adrenaline resulted in a full irreversible response to PAF. Aspirin, however, removed this synergism. In the remaining 4 patients, PAF induced a full response but aspirin abolished the synergism with adrenaline in 2 of them. In platelets from all controls aspirin failed to abolish the synergism between PAF and adrenaline. It is suggested that patients with myeloproliferative disorders lack - to varying degrees - an aspirin-independent mechanism which amplifies the primary response to PAF. Such a mechanism could involve the products of arachidonic acid metabolism catalyzed by lipoxygenase.
Viero
P
P
Cortelazzo
S
S
Barbui
T
T
de Gaetano
G
G
D000328:Adult; D000368:Aged; D001241:Aspirin / Q000494:pharmacology*; D004357:Drug Synergism; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D009196:Myeloproliferative Disorders / Q000097:blood*; D010972:Platelet Activating Factor / Q000502:physiology*; D010974:Platelet Aggregation / Q000187:drug effects*
D010972:Platelet Activating Factor; D001241:Aspirin; D004837:Epinephrine