title: Role of NO-cGMP pathway in ovine cervical relaxation induced by Erythroxylum caatingae Plowman.
abstract: Erythroxylum caatingae Plowman has a myorelaxing effect on smooth muscle tissue. We investigated the effect of the crude ethanolic extract of E. caatingae Plowman (Ec-EtOH) on the contractility of the ovine cervix. In an isometric system, circular strips were subjected to 90mM potassium (K(+)) or 30μM carbamylcholine (CCh)-induced contraction. We then exposed the tissue to cumulative concentrations of Ec-EtOH (1-729 μg/ml). In other bath solutions, the tissues were exposed to l-NG-nitroarginine methyl ester (l-NAME; 100μM), l-NAME (100μM)+l-arginine (300μM), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ; 5μM), 4-aminopyridine (4-AP; 3mM), tetraethylammonium (TEA; 0.3mM), glybenclamide (1μM), atosiban (10μM) or verapamil (3μM), followed by the addition of Ec-EtOH (1-729 μg/ml). We also evaluated the effect of cervical Ec-EtOH infusion (2mg) on cervical contractility in vivo. Ec-EtOH decreased cervical contractility induced by K(+) or CCh, and 729 μg/ml Ec-EtOH decreased 85.4±5.1% the amplitude of basal contractility in vitro, with an EC50 of 17.9±3.7 μg/ml. This effect of Ec-EtOH was prevented by l-NAME or ODQ. l-arginine impaired the blunting effect of l-NAME on cervical relaxation caused by Ec-EtOH. However, the potassium channel blockers 4-AP, TEA, and glybenclamide did not modify this myorelaxation triggered by Ec-EtOH. Ec-EtOH also decreased acetylcholine-induced contractions in tissue preincubated with verapamil. In addition, Ec-EtOH decreased ovine cervical contractions in vivo. Thus, Ec-EtOH had a relaxant effect on ovine cervical contractions. This may involve the nitric oxide signal, mediated by cGMP cellular transduction, and be related to intracellular calcium sequestration.
authors.affiliation: Course of Natural Resources in Semiarid.
authors.forename: K C
authors.initials: KC
authors.lastname: Santos
authors.affiliation: Laboratory of Physiology and Biotechnology of Animal Reproduction, Federal University of San Francisco Valley, Petrolina, PE, Brazil.
authors.forename: A P O
authors.initials: AP
authors.lastname: Monte
authors.affiliation: Course of Natural Resources in Semiarid.
authors.forename: J T
authors.initials: JT
authors.lastname: Lima
authors.affiliation: Course of Natural Resources in Semiarid.
authors.forename: L A A
authors.initials: LA
authors.lastname: Ribeiro
authors.affiliation: Course of Natural Resources in Semiarid. Electronic address: raimundo.palheta@univasf.edu.br.
authors.forename: R C
authors.initials: RC
authors.lastname: Palheta Junior
mesh_terms: D000818:Animals; D002584:Cervix Uteri / Q000187:drug effects*; D006152:Cyclic GMP / Q000378:metabolism*; D030921:Erythroxylaceae / Q000737:chemistry*; D005260:Female; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D012756:Sheep
chemical_list: D010936:Plant Extracts; D009569:Nitric Oxide; D006152:Cyclic GMP
keywords: Cervical contractility; Erythroxylum caatingae Plowman; Ovine cervix