title: Drosophila ryanodine receptors mediate general anesthesia by halothane.
abstract: BACKGROUND
  Although in vitro studies have identified numerous possible targets, the molecules that mediate the in vivo effects of volatile anesthetics remain largely unknown. The mammalian ryanodine receptor (Ryr) is a known halothane target, and the authors hypothesized that it has a central role in anesthesia.
  
  
  METHODS
  Gene function of the Drosophila Ryr (dRyr) was manipulated in the whole body or in specific tissues using a collection of mutants and transgenes, and responses to halothane were measured with a reactive climbing assay. Cellular responses to halothane were studied using Ca imaging and patch clamp electrophysiology.
  
  
  RESULTS
  Halothane potency strongly correlates with dRyr gene copy number, and missense mutations in regions known to be functionally important in the mammalian Ryrs gene cause dominant hypersensitivity. Tissue-specific manipulation of dRyr shows that expression in neurons and glia, but not muscle, mediates halothane sensitivity. In cultured cells, halothane-induced Ca efflux is strictly dRyr-dependent, suggesting a close interaction between halothane and dRyr. Ca imaging and electrophysiology of Drosophila central neurons reveal halothane-induced Ca flux that is altered in dRyr mutants and correlates with strong hyperpolarization.
  
  
  CONCLUSIONS
  In Drosophila, neurally expressed dRyr mediates a substantial proportion of the anesthetic effects of halothane in vivo, is potently activated by halothane in vitro, and activates an inhibitory conductance. The authors' results provide support for Ryr as an important mediator of immobilization by volatile anesthetics.
authors.affiliation: Biological Sciences Program, University of Maryland College Park, The Universities at Shady Grove Campus, 9630 Gudelsky Drive, Building 2, Room 4092, Rockville, MD 20850, USA.
authors.forename: Shuying
authors.initials: S
authors.lastname: Gao
authors.forename: David J
authors.initials: DJ
authors.lastname: Sandstrom
authors.forename: Harold E
authors.initials: HE
authors.lastname: Smith
authors.forename: Brigit
authors.initials: B
authors.lastname: High
authors.forename: Jon W
authors.initials: JW
authors.lastname: Marsh
authors.forename: Howard A
authors.initials: HA
authors.lastname: Nash
mesh_terms: D000595:Amino Acid Sequence; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D004331:Drosophila melanogaster; D006221:Halothane / Q000494:pharmacology*; D007103:Immobilization / Q000379:methods; D008297:Male; D008969:Molecular Sequence Data; D017354:Point Mutation / Q000187:drug effects / Q000502:physiology; D019837:Ryanodine Receptor Calcium Release Channel / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*
chemical_list: D018685:Anesthetics, Inhalation; D019837:Ryanodine Receptor Calcium Release Channel; D006221:Halothane