Dual effect of prostaglandins on isolated intraocular porcine ciliary arteries

. Purpose:  Prostaglandin analogues are used to reduce the intraocular pressure (IOP) in glaucoma, but also affect the tone of the arteries supplying the ciliary body. Previously, the effect of prostaglandins has been studied on the extraocular ciliary arteries, whereas the effect on intraocular ciliary arteries has not been studied in detail. Methods:  Intraocular long posterior porcine ciliary arteries were isolated and mounted in a myograph system for isometric tension recording, and the effects of PGF 2α , the prostaglandin analogue latanoprost, PGD 2 , PGE 2 , PGI 2 and the thromboxane analogue U46619 were studied in the presence and absence of selective receptor antagonists. Results:  The prostaglandins PGD 2 and PGE 2 induced relaxation at low concentrations (10 −9  – 3 × 10 −7   m ), which could be inhibited by blocking either the DP or the EP 4 receptor, whereas PGD 2 , PGE 2 , PGF 2α , latanoprost and U46619 induced contraction at high concentrations (10 −6  – 10 −5   m ), which could be inhibited by blocking the TP receptor. Additionally, blocking of the FP receptor induced a right‐shift of latanoprost‐induced contraction. Conclusions:  Prostaglandins with affinity to DP 1 and EP 4 receptors induce relaxation at low concentrations, and prostaglandins with affinity to TP and FP receptors induce contraction at high concentrations of intraocular porcine ciliary vessels in vitro . The findings may contribute to understanding the regulation of blood flow to the ciliary body.