Objective\ To investigate the effect of topical administ ration of prostaglandin F２α ,E2 (PGF２α,PGE２) in small dosage on
the normal
rabbits' eyes an d the hydrodynamic mediation of cyclic AMP(cAMP) in aqueous humor. Methods\ In randomized fashion,60 eyes of 30 rabbits were divided into 3 groups.Eyes in al l groups were administrated topically with one drop of 10μg PGF２α,or 10 μg PGE２or equal 0.9% saline solution.Intraocular pressure (IOP) were mea s ured on 10 eyes of every group at
different times.The cAMP production in aqueous humors were determinated in another 10 eyes in 2h after administration. Results\ IOP began to decrease in 0.5h after administration in PGF２α group and i n 1h in PGE２ group.The effect lasted for 5h and reached a maxinum in 2h, average 0.50kPa and 0.45kPa respectively.The cAMP production in aqueous humor wa s increased from (17.5±3.80)mmol/L of preadministration to (37.21±4.34) mmol/L i n PGE２group,but the change of cAMP was not obvious in PGF２α group . Conclusion\ Small dosage of PGF２α,PGE２ may decrease n ormal rabbits' IOP.The mechanism of PGE２ is related to the hydrodynamic m ediation of the second message cAMP in aqueous humor and PGF２α probably has a different second messenger system.\=