title: Bupivacaine induces short-term alterations and impairment in rat tendons.
abstract: BACKGROUND
  Toxicity of the local anesthetic bupivacaine (BV) has been a matter of debate across medical fields. Numerous in vitro studies demonstrate considerable toxicity of BV on various cell types.
  
  
  OBJECTIVE
  This study addresses the question of how tendon tissue responds to BV in vivo and in vitro.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  In vitro studies on cultured rat Achilles tendon-derived cells were performed with cell viability assays and cleaved caspase 3 immunocytochemistry. Quantitative reverse transcription-polymerase chain reaction, Western blotting, gelatin zymography, and a biomechanical testing routine were applied on rat Achilles tendons at 1 and 4 weeks after a single unilateral peritendinous injection of 0.5% BV. The BV-mediated cell death in tendons was estimated with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining and immunohistochemical detection of cleaved caspase 3.
  
  
  RESULTS
  Treatment of rat tendon-derived cells with 0.5% bupivacaine for 10 minutes had detrimental effects on cell viability, which can be reduced by N-acetyl-L-cysteine or reduction of extracellular calcium. In vivo, single peritendinous injections of BV caused apoptosis in endotenon cells and an increase of pro-matrix metalloproteinase-9 after 6 hours. The collagen ratio shifted toward collagen type III after 6 hours and 2 days; scleraxis messenger RNA (mRNA) expression was reduced by 87%. Maximum tensile load was reduced by 17.6% after 1 week.
  
  
  CONCLUSIONS
  Bupivacaine exerts a severe, reactive oxygen species-mediated effect on tendon cell viability in vitro in a time- and dose-dependent manner, depending on extracellular calcium concentration. Culture conditions need to be taken into account when in vitro data are translated into the in vivo situation. In vivo, administration of BV elicits a marked but temporary functional damage.
  
  
  CONCLUSIONS
  Local anesthetics cause short-term alterations in rat tendons, which, if occurring in humans to a similar extent, may be relevant regarding decreased biomechanical properties and increased vulnerability to tendon overload or injury.
authors: Paracelsus Medical University, Spinal Cord Injury and Tissue Regeneration Center Salzburg, Institute of Tendon and Bone Regeneration, Salzburg, Austria.
authors: Christine
authors: C
authors: Lehner
authors: Renate
authors: R
authors: Gehwolf
authors: Corinna
authors: C
authors: Hirzinger
authors: Daniel
authors: D
authors: Stephan
authors: Peter
authors: P
authors: Augat
authors: Mark
authors: M
authors: Tauber
authors: Herbert
authors: H
authors: Resch
authors: Hans-Christian
authors: HC
authors: Bauer
authors: Hannelore
authors: H
authors: Bauer
authors: Herbert
authors: H
authors: Tempfer
mesh_terms: D000125:Achilles Tendon / Q000166:cytology / Q000187:drug effects* / Q000473:pathology; D000779:Anesthetics, Local / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D001696:Biomechanical Phenomena; D002045:Bupivacaine / Q000633:toxicity*; D053148:Caspase 3 / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D015870:Gene Expression; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D012421:Rupture / Q000139:chemically induced; D013718:Tensile Strength; D013997:Time Factors
chemical_list: D000779:Anesthetics, Local; D051792:Basic Helix-Loop-Helix Proteins; D002045:Bupivacaine; D053148:Caspase 3; D003094:Collagen; D020780:Matrix Metalloproteinase 9; D012333:RNA, Messenger; C503819:Scx protein, rat
keywords: biomechanics; bupivacaine toxicity; extracellular calcium; local anesthetics; tendon