Vasoactive Responses of U46619, PGF2α, Latanoprost, and Travoprost in Isolated Porcine Ciliary Arteries

PURPOSE. To compare the vasoactive properties of the prostanoids U46619 (thromboxane A 2 analogue), prostaglandin F 2α (PGF 2α ), latanoprost free acid, and travoprost free acid in isolated porcine ciliary arteries. METHODS. In a myograph system (isometric force measurement), quiescent vessels were exposed (cumulatively) to U46619, PGF 2α , latanoprost, or travoprost (0.1 nM-0.1 mM). Experiments were also conducted in the presence of SQ 29548 (TP-receptor antagonist; 3-10 μM) or AL-8810 (FP-receptor antagonist; 3-30 μM). Contractions were expressed as the percentage of 100 mM potassium chloride-induced contractions. RESULTS. In quiescent vessels, contractions (concentration-response curves) induced by (0.1 mM) PGF 2α (87.9% ± 3.5%), U46619 (66.7% ± 4.1%), and latanoprost (62.9% ± 3.6%) were more pronounced (P ≤ 0.001) than those induced by travoprost (23.0% ± 4.4%). Concentration-response curves for PGF 2α , latanoprost, and travoprost were preceded by a smaller contraction peak (0.1 μM) that was higher (P ≤ 0.05) for travoprost (24.4% ± 2.8%) than for PGF 2α (12.9% ± 4.6%), but not different (P = 0.58) from latanoprost (22.0% ± 3.0%). The 50% maximal contraction (PD 50 : negative log M concentration) of U46619 (-8.05 ± 0.13) was lower (P ≤ 0.001) than those of latanoprost (-5.65 ± 0.10), PGF 2α (-5.49 ± 0.14), and travoprost (-5.12 ± 0.52). Contractions were inhibited (P ≤ 0.05-0.001) either by SQ 29548 or AL-8810. CONCLUSIONS. In isolated porcine ciliary arteries, all prostanoids tested induced contractions. Among them, travoprost appeared to be the least potent and U46619 the most efficient.