Summary
We have used the DNase I inhibition assay to study changes in G-actin after platelet
activation in platelet-rich plasma (PRP) induced by ADP. Because of problems associated
with depolymerization of F-actin after lysis of ADP-activated platelets in the presence
of plasma, G-actin was measured using a lysis buffer that contained formaldehyde to
prevent any depolymerization of F-actin.
Different patterns of response were seen depending on the concentration of ADP used,
and these were modified by avoiding aggregation by either not stirring the sample
or by adding EDTA. The results show rapid conversion of G-actin to F-actin in association
with shape change, and there is a further decrease in G-actin associated with irreversible
platelet aggregation. Thus evidence is presented that actin polymerization occurs
in two phases after ADP stimulation.
