Influence of verapamil and diltiazem on aggregatory responses in cat and rabbit platelet rich plasma.

The effects of verapamil and diltiazem, calcium channel blockers, on aggregatory responses to ADP, arachidonic acid (AA), U46619, a thromboxane A2 mimic, and prostaglandin H2 (PGH2) were investigated in cat and rabbit platelet rich plasma. Results of the present study demonstrate that verapamil and diltiazem inhibit cat or rabbit platelet aggregation induced by ADP, AA, U46619, and PGH2. Furthermore, the present experiments provide the first reported data showing the inhibitory actions of calcium channel blockers on aggregatory responses to PGH2, the pivotal endoperoxide intermediate of arachidonic acid metabolism. Since verapamil and diltiazem at similar concentrations inhibited aggregatory responses to a similar degree in platelet rich plasma from cat or rabbit, the present data indicate that the influence of verapamil and diltiazem on platelet aggregation may be independent of species studied as well as nonspecific in nature.