title: The marine polyether gambierol enhances muscle contraction and blocks a transient K(+) current in skeletal muscle cells.
abstract: Gambierol is a complex marine toxin first isolated with ciguatoxins from cell cultures of the toxic dinoflagellate Gambierdiscus toxicus. Despite the chemical complexity of the polycyclic ether toxin, the total successful synthesis of gambierol has been achieved by different chemical strategies. In the present work the effects of synthetic gambierol on mouse and frog skeletal neuromuscular preparations and Xenopus skeletal myocytes have been studied. Gambierol (0.1-5 muM) significantly increased isometric twitch tension in neuromuscular preparations stimulated through the motor nerve. Less twitch augmentation was observed in directly stimulated muscles when comparing twitch tension-time integrals obtained by nerve stimulation. Also, gambierol induced small spontaneous muscle contraction originating from presynaptic activity that was completely inhibited by d-tubocurarine. Gambierol slowed the rate of muscle action potential repolarization, triggered spontaneous and/or repetitive action potentials, and neither affected action potential amplitude nor overshoot in skeletal muscle fibers. These results suggest that gambierol through an action on voltage-gated K(+) channels prolongs the duration of action potentials, enhances the extent and time course of Ca(2+) release from the sarcoplasmic reticulum, and increases twitch tension generation. Further evidence is provided that gambierol at sub-micromolar concentrations blocks a fast inactivating outward K(+) current that is responsible for action potential prolongation in Xenopus skeletal myocytes.
authors.affiliation: CNRS, Institut de Neurobiologie Alfred Fessard - FRC2118, Laboratoire de Neurobiologie Cellulaire et Moléculaire - UPR9040, 91198 Gif sur Yvette cedex, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Schlumberger
authors.forename: Gilles
authors.initials: G
authors.lastname: Ouanounou
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Girard
authors.forename: Makoto
authors.initials: M
authors.lastname: Sasaki
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Fuwa
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Louzao
authors.forename: Luis M
authors.initials: LM
authors.lastname: Botana
authors.forename: Evelyne
authors.initials: E
authors.lastname: Benoit
authors.forename: Jordi
authors.initials: J
authors.lastname: Molgó
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002922:Ciguatoxins / Q000494:pharmacology*; D005260:Female; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D014403:Tubocurarine / Q000494:pharmacology; D014981:Xenopus; D035964:Oxocins
chemical_list: D002922:Ciguatoxins; D026902:Potassium Channel Blockers; D014403:Tubocurarine; C435770:gambierol; D035964:Oxocins