Inhibition of platelet adhesion to collagen by cGMP-elevating agents

In the present study, we examined the effects and action mechanisms of cGMP-elevating agents on platelet adhesion to collagen fiber. YC-1, a nitric oxide (NO)-independent activator of soluble guanylate cyclase, inhibited both initial and long-term platelet adhesion to collagen, and the inhibitory effect was potentiated by dipyridamole, a selective inhibitor of cGMP-specific phosphodiesterase. Sodium nitroprusside (SNP), a NO-donor, and 8-bromo-cGMP also inhibited the initial platelet adhesion, but inhibited long-term adhesion only in the presence of dipyridamole. Collagen-induced intracellular Ca2+ mobilization and actin polymerization were prevented by YC-1, SNP and 8-bromo-cGMP. Since blockade of Ca2+ mobilization and actin polymerization caused by collagen led to decrease of platelet adhesion, we suggest that the inhibitory activity of cGMP-elevating agents on the adhesion of platelets to collagen is resulting from interference of these signaling pathways.