Effects of phalloidin on platelet release.

The effect on platelet of phalloidin, a reagent forming phalloidin-actin polymer, was studied. Phalloidin suppressed ATP release but did not affect aggregation after the stimulation with ADP or A23187, although the amount of F-actin was increased by stimulation. The suppression was correlated to the preincubation time and to the concentration of phalloidin.