Nifedipine Enhances the Relaxant Effects of Cyclo-Oxygenase Inhibitors on the Bovine Ciliary Muscle

Abstract Background/Aims: The inhibition of cyclo-oxygenase (COX) enzymes and the blockade of Ca2+ channels play an important role in the regulation of smooth muscle relaxation. This study was designed to investigate the relaxant effects of celecoxib, DFU (5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulphonyl)phenyl-2(5H)-furanone), and indomethacin, cyclo-oxygenase (COX-1 and −2) inhibitors, in the absence or presence of a nifedipine, l-type Ca2+ channel blocker, on bovine ciliary muscle. Methods: Ciliary muscle strips (n = 12) were mounted in organ baths and tested for changes in isometric tension in response to celecoxib, DFU, and indomethacin. The relaxant effects of celecoxib, DFU, and indomethacin on carbachol-induced contractions in the presence or absence of nifedipine were investigated. Results: Celecoxib (10−7–10−4 M), DFU (10−7–10−4 M), indomethacin (10−7–10−4 M), and nifedipine (10−7–10−4 M) inhibited the carbachol-induced contractions in a concentration-dependent manner. The Emax value of indo...