Abstract
Abstract: :
Purpose: In isolated porcine ciliary arteries, to investigate vasoactive properties of the prostanoids U46619 (thromboxane A2 analog), prostaglandin F2alpha (PGF2alpha), latanoprost free acid, and travoprost free acid. Methods: In a myograph system (isometric force measurement), either quiescent or 30 µM KCl pre–contracted vessels were exposed (cumulative manner) to U46619, PGF2alpha, latanoprost, or travoprost (0.1 nM – 0.1 mM). In quiescent vessels experiments were also conducted in the presence of SQ29548 (TP–receptor antagonist; 3 – 10 µM) or AL–8810 (FP–receptor antagonist; 3 – 30 µM). Contractions were expressed in percent of 100 mM KCl–induced contractions. Results: In quiescent vessels, prostanoids induced contractions that were, at a concentration of 0.1 mM, significantly (P < 0.001) higher for U46619 (66.7 ± 4.1%), PGF2alpha (87.9 ± 3.5%), and latanoprost (62.9 ± 3.6%), than for travoprost (23.0 ± 4.4%). Contractions for PGF2alpha, latanoprost, and travoprost were bi–phasic with a first contraction observed at a concentration of 0.1 µM that was for travoprost (24.4 ± 2.8%) significantly (P < 0.02) higher than for PGF2alpha (12.9 ± 4.6%) but not significantly (P = 0.58) different from latanoprost (22.0 ± 3.0%). All these contractions were significantly (P < 0.05 – 0.001) inhibited either by SQ29548 or AL–8810. In pre–contracted vessels, only contractions and no relaxations were observed. Conclusions: In isolated porcine ciliary arteries and at high concentrations, U46619, PGF2alpha, and latanoprost induced contractions that were much higher than those evoked by travoprost, contractions that could be inhibited either by SQ29548 (TP–receptor antagonist) or by AL–8810 (FP–receptor antagonist).
Keywords: intraocular pressure • blood supply • pharmacology