title: Radioprotective effect of lidocaine on neurotransmitter agonist-induced secretion in irradiated salivary glands.
abstract: BACKGROUND
  Previously we verified the radioprotective effect of lidocaine on the function and ultrastructure of salivary glands in rabbits. However, the underlying mechanism of lidocaine's radioprotective effect is unknown. We hypothesized that lidocaine, as a membrane stabilization agent, has a protective effect on intracellular neuroreceptor-mediated signaling and hence can help preserve the secretory function of salivary glands during radiotherapy.
  
  
  METHODS
  Rabbits were irradiated with or without pretreatment with lidocaine before receiving fractionated radiation to a total dose of 35 Gy. Sialoscintigraphy and saliva total protein assay were performed before radiation and 1 week after the last radiation fraction. Isolated salivary gland acini were stimulated with either carbachol or adrenaline. Ca(2+) influx in response to the stimulation with these agonists was measured using laser scanning confocal microscopy.
  
  
  RESULTS
  The uptake of activity and the excretion fraction of the parotid glands were significantly reduced after radiation, but lidocaine had a protective effect. Saliva total protein concentration was not altered after radiation. For isolated acini, Ca(2+) influx in response to stimulation with carbachol, but not adrenaline, was impaired after irradiation; lidocaine pretreatment attenuated this effect.
  
  
  CONCLUSIONS
  Lidocaine has a radioprotective effect on the capacity of muscarinic agonist-induced water secretion in irradiated salivary glands.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University of Luebeck, Luebeck, Germany. suyuxiong@hotmail.com
authors.forename: Yu-xiong
authors.initials: YX
authors.lastname: Su
authors.forename: Geza A
authors.initials: GA
authors.lastname: Benedek
authors.forename: Peter
authors.initials: P
authors.lastname: Sieg
authors.forename: Gui-qing
authors.initials: GQ
authors.lastname: Liao
authors.forename: Andreas
authors.initials: A
authors.lastname: Dendorfer
authors.forename: Birgit
authors.initials: B
authors.lastname: Meller
authors.forename: Dirk
authors.initials: D
authors.lastname: Rades
authors.forename: Matthias
authors.initials: M
authors.lastname: Klinger
authors.forename: Samer G
authors.initials: SG
authors.lastname: Hakim
mesh_terms: D000818:Animals; D005720:Gamma Rays / Q000009:adverse effects*; D008012:Lidocaine / Q000494:pharmacology*; D018721:Muscarinic Agonists / Q000494:pharmacology*; D010306:Parotid Gland / Q000187:drug effects / Q000528:radiation effects; D011817:Rabbits; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D012469:Salivary Glands / Q000187:drug effects* / Q000528:radiation effects*
chemical_list: D018721:Muscarinic Agonists; D011837:Radiation-Protective Agents; D008012:Lidocaine
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