Abstract
Prostaglandln (PG)E1, 0.10 [mu]g or PGE2 administered into the anterior chamber of the rabbit eye causes a large elevation of intraocular pressure (IOP) and also miosis. The threshold dose for both effects is about 0. 01 [mu]g. PGF1a in doses of 5 [mu]g, administered in a similar manner, causes none of the above effects although 125 [mu]g PGF1[alpha] so administered causes miosis but no significant IOP elevation. In cats, 2. 5 [mu]g PGE''s given the same way do not affect IOP but do elicit a long-lasting miosis, even in the atroplnlzed eye. Given intravenously, PGE''s raise the IOP while simultaneously lowering blood pressure; the iv threshold dose is about 0. 25 [mu]g. The miotic effect caused by PG is interpreted as meaning some direct effect on iris smooth muscle, and the IOP change in the rabbits is interpreted as meaning an elevation of aqueous humor production with intraocular vasodilation possibly playing some contributory role. PG does not appear to reduce the rate of out-flow of aqueous humor and, in fact, may cause a slight increase in this rate.