Abstract
Purpose: :
Topical application of antiglaucomatous prostaglandin (PG) analogues, Latanoprost, Unoprostone and Tafluprost, were reported to increase ocular blood flow. To investigate the vasodilatory mechanism of these drugs, we have investigated the effect of these drugs on isolated rabbit and mouse ciliary arteries in vitro.
Methods: :
Under the dissecting microscope, ciliary arteries were prepared from albino rabbit eyes and mounted in a myograph system. The effects of PG analogues were investigated using isometric tension recoding methods. We further investigated the effects of these drugs on changes in intracellular Ca2+ concentrations ([Ca2+]i) in mouse ciliary arteries by using the Ca2+-sensitive dye fura-2 as an indicator.
Results: :
These three PG analogues induced dose-dependent relaxations in rabbit ciliary artery that were pre-contracted with high-K solution. Application of NG-nitro-L-arginine methylester (300µM) or indomethacin (10µM) did not affect this relaxation. These three PG analogues significantly decreased the [Ca2+]i in mouse ciliary artery elevated by high-K.
Conclusions: :
Antiglaucomatous PG analogues relaxed and decreased [Ca2+]i in rabbit or mouse ciliary arteries. The mechanism of vascular smooth muscle relaxation by PG analogues does not depend on NO or intrinsic PG production.
Keywords: blood supply • calcium • nitric oxide