Latanoprost is a vasoconstrictor in isolated porcine ciliary arteries

Purpose: The purpose of this study was to assess the vasoconstrictor effect of the prostaglandin F-2 alpha analog latanoprost in isolated porcine cili ary arteries. Material and Methods: With a myograph system to measure isometric forces, p orcine ciliary arteries were exposed, in a cumulative manner, to increasing concentrations of latanoprost (0.1 nM - 0.1 mM). Experiments were conducte d in quiescent vessels as well as in vessels precontracted with potassium c hloride (KCl; 40 mM) or endothelin-1 (10 nM). Contractions were expressed i n percent of 100 mM KCI-induced contraction. Results: In a concentration dependent manner latanoprost induced significan t (p <0.001) contractions in quiescent vessels (maximum: 68 +/- 3 %, n = 5; PD50: 5.7 +/- 0.1). In KCI or in endothelin-l precontracted vessels latano prost did not evoke any relaxation but in contrast significant (p <0.001) c ontractions (maximum: 33 +/- 4%, n = 5 and 26 +/- 6%, n = 8, respectively). Conclusions: Latanoprost has a vasoconstrictor effect in isolated porcine c iliary arteries. No relaxation could be observed. The clinical relevance of this finding requires further evaluation.