Inhibition of platelet function by A02131-1, a novel inhibitor of cGMP-specific phosphodiesterase, in vitro and in vivo.
The effect of A02131-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzyl thieno (3,2-c)pyrazole], a cGMP-specific phosphodiesterase (PDE) inhibitor, on platelet function was investigated. The compound was found to inhibit the aggregation of and adenosine triphosphate (ATP) release from human platelet-rich plasma and washed platelets that were induced by aggregation inducing drugs such as arachidonic acid (AA), collagen, U46619, platelet-activating factor (PAF), adenosine diphosphate (ADP) and A23187, and the inhibitory effect was concentration-dependent. A02131-1 also disaggregated the performed platelet aggregates induced by these inducers. Thromboxane B2 (TXB2) formations caused by collagen, PAF, ADP, and A23187 were inhibited by A02131-1 at concentrations that did not affect the AA-induced formation of TXB2 and prostaglandin D2 (PGD2). A02131-1 suppressed both the generation of inositol 1,4,5-triphosphate (IP3) and the increase of intracellular Ca2+ concentration stimulated by these aggregation inducers. A02131-1 was shown to increase the cAMP and cGMP levels in platelets and the extent was found to be dependent on concentration as well as time. A02131-1 increased the cAMP level much more slowly than the cGMP level. Activities of adenylate cyclase, guanylate cyclase, and PDEs (type I and III) were not altered by A02131-1. However, the activity of cGMP-specific PDE (type V) was inhibited by A02131-1. The antiplatelet aggregation activity and the effect on raising cAMP level of A02131-1 were both potentiated by prostaglandin E1 (PGE1). In the mouse tail bleeding test, A02131-1 was clearly shown to be more effective than dipyridamole in prolonging the tail bleeding time of conscious mice. These data indicate that A02131-1 is a cGMP-specific PDE (type V) inhibitor in human platelets.
Yu
S M
SM
Department of Pharmacology, Chang Gung College of Medicine and Technology, Tao-Yuan, Taiwan.
Tsai
S Y
SY
Kuo
S C
SC
Ou
J T
JT
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000818:Animals; D001792:Blood Platelets / Q000502:physiology*; D002478:Cells, Cultured; D006801:Humans; D051379:Mice; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D015539:Platelet Activation / Q000187:drug effects* / Q000502:physiology
D010726:Phosphodiesterase Inhibitors; D015106:3',5'-Cyclic-GMP Phosphodiesterases