The aim of this study was to investigate the in vivo effects of 50 mg/kg (i.p.)
naftazone or
ticlopidine on platelet functions in the rat. An automated
isotope monitoring system (Aims plus) was used to determine the height of platelet aggregation and disaggregation (measured by the area under the curve, AUC) of 111indium-labelled platelets activated by
ADP (10 microg/kg i.v.) or
collagen (50 microg/kg i.v.).
Fibrinogen-binding experiments were carried out with activated platelets in whole blood and measured by flow cytometry.
Naftazone reduced the height of platelet aggregation induced by
ADP compared with controls (P = 0.024).
Ticlopidine-treated rats gave similar results (P = 0.008). Platelet disaggregation, following the aggregation induced by
collagen, was significantly increased in
naftazone-treated rats compared with controls (P = 0.003). Similar results were observed with
ticlopidine-treated rats (P = 0.002).
Fibrinogen binding to 2.5 or 5 microM
ADP-stimulated platelets, from
naftazone-treated rats, were significantly reduced compared with controls (P = 0.05 and 0.04 respectively). These results show that
naftazone has similar inhibitory effects on rat platelet functions as ticloplidine. In conclusion,
naftazone could be a useful agent to modulate platelet function in patients with
cardiovascular disease.