title: Comparison of the inhibitory effects of cromakalim and pinacidil (potassium channel openers) with those of oxybutynin on stimulated guinea pig and rabbit detrusor muscle strips.
abstract: To compare the inhibitory effects of a new group of smooth muscle relaxants, the potassium channel openers cromakalim and pinacidil, with those of oxybutynin on detrusor muscle stimulation in animals. Detrusor strips of guinea pigs (n=16) and rabbits (n=20) were mounted in organ bath for recording of isometric tension. Alpha,beta-methylene ATP (10(-7), 10(-6), 10(-5) M), carbachol (10(-6), 10(-5), 3 x 10(-5), 5 x 10(-5) M) and transmural electrical-field stimulation (TES) were applied and concentration-response curves in the absence or presence of cromakalim (10(-6), 10(-5) M), pinacidil (10(-5), 5 x 10(-5) M) and oxybutynin (10(-5), 5 x 10(-5) M) were generated. All curves were displaced to the right in a concentration-dependent manner. The order of potency of inhibition was as follows: alpha,beta-methylene ATP (pinacidil>oxybutynin>cromakalim in guinea pigs; pinacidil>cromakalim>oxybutynin in rabbits); TES (pinacidil>cromakalim>oxybutynin in guinea pigs; cromakalim>oxybutynin>pinacidil in rabbits); carbachol (oxybutynin>pinacidil>cromakalim in guinea pigs; oxybutynin>cromakalim>pinacidil in rabbits). Cromakalim and pinacidil mainly inhibited purinergic-induced (alpha,beta-methylene ATP and TES) detrusor contractions.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al-Ain. rizk.diaa@uaeu.ac.ae
authors.forename: D E
authors.initials: DE
authors.lastname: Rizk
authors.forename: K
authors.initials: K
authors.lastname: Arafat
authors.forename: T Y
authors.initials: TY
authors.lastname: El-Sharkawy
mesh_terms: D000818:Animals; D018680:Cholinergic Antagonists / Q000627:therapeutic use*; D019806:Cromakalim / Q000627:therapeutic use*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008333:Mandelic Acids / Q000627:therapeutic use*; D009130:Muscle, Smooth / Q000187:drug effects*; D020110:Pinacidil / Q000627:therapeutic use*; D011817:Rabbits; D001743:Urinary Bladder / Q000187:drug effects*; D014665:Vasodilator Agents / Q000627:therapeutic use*
chemical_list: D018680:Cholinergic Antagonists; D008333:Mandelic Acids; D014665:Vasodilator Agents; D019806:Cromakalim; D020110:Pinacidil; C005419:oxybutynin