OBJECTIVE:To study the ADR mechanism of conjunctival hyperemia in model rats with prostacyclin-induced high intraocular pressure. METHODS:50 rats were randomly divided into normal control group,model group,prostacyclin low-dose, medium-dose,high-dose groups(100,200,400 mg/kg),10 in each group. Except for normal control group,right eyes of rats in other groups were established high intraocular pressure model,dropping corresponding medicine once a day,for 1 week. After last administration,the right eyes cornel peripheral corneal endothelial cells of rats in each group were isolated in vitro and cultured. Vascular endothelial cell viability,cell apoptosis and proliferation-related factor(Ki-76),apoptosis-related factors(Bad,Bax),in-hibito of apoptosis-related factors (Bcl-2,Bcl-xl) protein expressions were detected. RESULTS:Compared with normal control group,vascular endothelial cell viability in model group were obviously decreased;apoptosis rate was obviously increased;Bad, Bax protein expressions were obviously enhanced;Bcl-2,Bcl-xl,Ki-76 protein expressions were obviously weakened,with statisti-cal significances (P<0.05 or P<0.01). Compared with model group,vascular endothelial cell viability in prostacyclin low-dose,medium-dose,high-dose groups were obviously decreased;apoptosis rate was obviously increased;Bcl-2,Bcl-xl protein expres-sions were obviously weakened,with statistical significances(P<0.05 or P<0.01);the Bad,Bax protein expressions in prostacy-clin medium-dose,high-dose groups were obviously enhanced(P<0.05 or P<0.01),the other indexes had no statistical differenc-es(P>0.05). CONCLUSIONS:Prostacyclin may cause conjunctival hyperemia through promoting the apoptosis of cornel peripher-al corneal endothelial cells of model rats with high intraocular pressure and decreasing the cell viability.