title: Modification of Bupivacaine-Induced Myotoxicity with Dantrolene and Caffeine In Vitro.
abstract: BACKGROUND
  Local anesthetics, especially bupivacaine, have myotoxic effects in clinically used concentrations and context. Detailed mechanisms of these effects are unknown, but an increase in intracellular calcium levels is suspected to be the most important trigger. Dantrolene and caffeine modify cellular calcium release from the sarcoplasmic reticulum. The aim of our study was to investigate the effect of dantrolene and caffeine on bupivacaine-induced myotoxicity in vitro.
  
  
  METHODS
  A cell culture model of primary muscle cells of BALB/c AnNCrl mice was established. Cells were incubated simultaneously with increasing concentrations of bupivacaine, dantrolene, and caffeine. The fraction of dead cells was calculated after staining with propidium iodide and analysis by flow cytometry. The half-maximal inhibitory concentration of bupivacaine was calculated for each concentration. Group differences were determined by using 1-way analysis of variances with subsequent post hoc 1-way Dunnett t test.
  
  
  RESULTS
  Both dantrolene and caffeine alone had no effect on muscle cell survival. Increasing concentrations of bupivacaine caused increasing cell death. Dantrolene dose-dependently reduced the fraction of necrotic cells, whereas caffeine dose-dependently increased the fraction of dead cells.
  
  
  CONCLUSIONS
  Dantrolene attenuated, and caffeine enhanced, bupivacaine-induced myotoxicity, presumably by modifying sarcoplasmic calcium release. This indicates that intracellular calcium release is an important factor for local anesthetic-induced cell death.
authors.affiliation: From the *Department of Anesthesiology, University Hospital Regensburg, Regensburg, Germany; and †Department of Anesthesiology and Intensive Care Medicine, Klinikum Ludwigshafen, Ludwigshafen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Plank
authors.forename: Petra
authors.initials: P
authors.lastname: Hofmann
authors.forename: Michael
authors.initials: M
authors.lastname: Gruber
authors.forename: Gabriele
authors.initials: G
authors.lastname: Bollwein
authors.forename: Bernhard M
authors.initials: BM
authors.lastname: Graf
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Zink
authors.forename: Thomas
authors.initials: T
authors.lastname: Metterlein
mesh_terms: D000779:Anesthetics, Local / Q000633:toxicity*; D000818:Animals; D017302:Annexins / Q000378:metabolism; D002045:Bupivacaine / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D002110:Caffeine / Q000627:therapeutic use*; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D003620:Dantrolene / Q000627:therapeutic use*; D066298:In Vitro Techniques; D051379:Mice; D008807:Mice, Inbred BALB C; D009125:Muscle Relaxants, Central / Q000627:therapeutic use*; D009135:Muscular Diseases / Q000139:chemically induced* / Q000517:prevention & control*; D009336:Necrosis; D061251:Primary Cell Culture
chemical_list: D000779:Anesthetics, Local; D017302:Annexins; D000697:Central Nervous System Stimulants; D009125:Muscle Relaxants, Central; D002110:Caffeine; D003620:Dantrolene; D002045:Bupivacaine