title: cAMP is an important messenger for ADP-induced platelet aggregation.
abstract: In rat platelets, basal cAMP levels were not changed upon stimulation with ADP and it was concluded that cAMP is not an important messenger for ADP-induced aggregation (Savi et al., Blood Coagul Fibrinolysis, 1996; 7: 249-52). In the present study, the effects of prostaglandin E(1) (PGE(1)) and ADP on human platelet aggregation, cAMP generation and VASP phosphorylation were studied. Phosphorylation of the protein kinase A (PKA) substrate VASP and inhibition of platelet aggregation by PGE(1) occurred without measurable changes in cellular cAMP levels. In addition, a marked inhibition of basal VASP phosphorylation by ADP was observed. It is concluded that cAMP determinations do not necessarily detect a possible activation or inhibition of the cAMPPKA pathway in platelets. Thus, cAMP might well be an important second messenger for ADP-induced platelet aggregation.
authors.affiliation: Institut für Pharmakologie und Klinische Pharmakologie, Heinrich-Heine-Universität Düsseldorf, Germany.
authors.forename: A A
authors.initials: AA
authors.lastname: Weber
authors.forename: T
authors.initials: T
authors.lastname: Hohlfeld
authors.forename: K
authors.initials: K
authors.lastname: Schrör