Absence of vasoactive properties of travoprost in isolated porcine ciliary arteries

Background: Ocular blood flow dysregulation is considered to be a risk factor associated with the optic neuropathy observed in glaucoma patients. The present study evaluates the vasoactive effect of the ocular hypotensive agent travoprost (Travatan(R)) on isolated pig ciliary arteries. Material and methods: Isometric forces were measured with a myograph system. Quiescent vessels were exposed in a cumulative manner to increasing concentrations (0.1 nM-0.1 mM) of travoprost ([+]-fluprostenol). Vessels pre-contracted with 100 mM potassium chloride (KCl) or 10 nM endothelin-1 were also exposed in a similar manner to travoprost. Time-control experiments without travoprost were always run in parallel. In quiescent vessels, contractions were expressed in percent of 100 mM KCl-induced contractions. In vessels pre-contracted with endothelin-1, relaxations were expressed in percent of the maximal contraction induced by this peptide, while in those pre-contracted with KCl, relaxations were expressed in percent of the plateau-contraction reached 30 minutes after the application of this drug. Results: In quiescent vessels, travoprost had no statistically significant vasoconstrictive effect. In KCl- or in endothelin-1 pre-contracted vessels, travoprost had no statistically significant vasorelaxing effect. Conclusions: Although the clinical relevance of the results of this study for patients treated with travoprost (Travatan(R)) needs to be further investigated, travoprost appears to have no vasoconstrictive properties in isolated porcine ciliary arteries.