Influence of phentolamine on platelet aggregation, thromboxane B2 production and release reaction.
In this study the in vitro influence of phentolamine on platelet aggregating responses, thromboxane B2 (TxB2) production and intraplatelet cyclic AMP (cAMP) content has been investigated. The drug exerts a dose-dependent inhibitory effect on aggregating response to ADP, PAF, collagen, thrombin, sodium arachidonate and ionophore A 23187. Inhibiting phentolamine concentrations prevent also platelet release reaction and TxB2 synthesis. No significant influence on intraplatelet cAMP levels has been observed. The pre-incubation with low concentrations of ionophore A 23187 overcomes phentolamine inhibition of collagen-induced platelet aggregation. Our results provide evidence that phentolamine modulates the human platelet function and that its effects could also be related to a decrease of Ca++ availability.
Anfossi
G
G
Institute of Internal Medicine, University of Turin, Ospedale S. Luigi Gonzaga-Orbassano, Torino, Italy.
Trovati
M
M
Mularoni
E
E
Lanzio
M
M
Massucco
P
P
Emanuelli
G
G
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D003094:Collagen / Q000494:pharmacology; D000242:Cyclic AMP / Q000097:blood; D006801:Humans; D066298:In Vitro Techniques; D010646:Phentolamine / Q000494:pharmacology*; D010972:Platelet Activating Factor / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects*; D013917:Thrombin / Q000494:pharmacology; D013929:Thromboxane B2 / Q000096:biosynthesis* / Q000378:metabolism
D001095:Arachidonic Acids; D010972:Platelet Activating Factor; D016718:Arachidonic Acid; D000001:Calcimycin; D013929:Thromboxane B2; D000244:Adenosine Diphosphate; D003094:Collagen; D000242:Cyclic AMP; D013917:Thrombin; D010646:Phentolamine