Table 1.

Comparison of agonist EC₅₀ values for different measures of platelet activation

Measure of activation	Convulxin	SFLLRN	AYPGKF	ADP	U46619	PGE2
Cytosolic Ca2+	5.3 nM	15.2 μM	112.4 μM	1.17 μM	1.19 μM	24.6 μM
PAC-1	1.6 nM	4.4 μM	267 μM	595 nM	n/a	11.5 μM
anti-CD62P	2.4 nM	6.6 μM	223 μM	371 nM	n/a	49.4 μM

Calculated EC₅₀ values for platelet activation measured by binding of PAC-1 and anti-CD62P antibodies to ntegrin α_IIbβ₃ and P-selectin respectively and cytosolic Ca²⁺ values that were obtained previously. Platelet rich plasma was incubated with each of the five activating agonists, while PGE₂ was coincubated with 15 μM SFLLRN. U46619 did not elicit significant antibody binding.