Summary
Earlier studies showed that platelet retention was low in disturbed blood and was
restored by incubating the blood with apyrase. The low values appeared to be due to
ADP-induced inhibition. Patients with von Willebrand’s disease and some patients with
cardiac valve abnormalities or prostheses had reduced platelet retention in glass
bead columns. Although retention was often increased by incubating the blood with
apyrase, it never reached normal values. Retention in normal blood was low when short
columns were used and was also increased by apyrase. Thus, ADP-induced inhibition
is apparently present even in carefully drawn blood and is probably not responsible
for the poor retention in von Willebrand’s disease and cardiac valve abnormalities.
