title: Time course of mitochondrial metabolism alterations to repeated injections of bupivacaine in rat muscle.
abstract: OBJECTIVE
  Bupivacaine-induced myotoxicity is associated with mitochondrial bioenergetic alterations. The impact of the duration of bupivacaine treatment on mitochondrial energy production remains undetermined. Here, we assessed, in vivo, the alteration of mitochondrial metabolism following different durations of bupivacaine exposure (40, 56, or 112 hr) that correspond to 5, 7, or 14 repeated injections of 0.25% bupivacaine, respectively.
  
  
  METHODS
  Rats were divided randomly into seven different groups: one control group (no catheter); three groups with normal saline injections (1 mL x kg(-1)) every eight hours via a femoral nerve catheter for 40, 56, and 112 hr, respectively; and three groups with 0.25% bupivacaine injections (1 mL x kg(-1)) every eight hours via a femoral nerve catheter for 40, 56, and 112 hr. Psoas and gracilis muscle samples located within the bupivacaine infusion-diffusion space were investigated. To estimate mitochondrial respiratory capacity, the protein content of the mitochondrial respiratory chain apparatus was evaluated by measuring citrate synthase activity. To measure mitochondrial respiratory function, adenosine diphosphate-stimulated oxygen consumption was measured by polarography in saponin-skinned muscle fibres using glutamate-malate or succinate as energy substrates.
  
  
  RESULTS
  In psoas and gracilis muscles, saline solution had no effect on the two mitochondrial parameters. Bupivacaine induced a significant decrease in the citrate synthase activity in psoas (r(2) = 0.74; P < 0.001) and gracilis muscle (r(2) = 0.52; P < 0.001), and there was a significant decrease in the adenosine diphosphate-stimulated oxygen consumption using glutamate or succinate as substrates in both muscles (P < 0.001).
  
  
  CONCLUSIONS
  The severity of bupivacaine-induced myotoxicity is closely linked to the duration of bupivacaine exposure in the muscle fibres located close to the catheter tip.
authors.affiliation: Laboratoire de physiopathologie mitochondriale, Université Victor Segalen Bordeaux 2, 33076, Bordeaux, France. karine.nouette-gaulain@chu-bordeaux.fr
authors.forename: Karine
authors.initials: K
authors.lastname: Nouette-Gaulain
authors.forename: Sophie
authors.initials: S
authors.lastname: Bringuier
authors.forename: Mireille
authors.initials: M
authors.lastname: Canal-Raffin
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bernard
authors.forename: Sandrine
authors.initials: S
authors.lastname: Lopez
authors.forename: Christophe
authors.initials: C
authors.lastname: Dadure
authors.forename: Françoise
authors.initials: F
authors.lastname: Masson
authors.forename: Jacques
authors.initials: J
authors.lastname: Mercier
authors.forename: François
authors.initials: F
authors.lastname: Sztark
authors.forename: Rodrigue
authors.initials: R
authors.lastname: Rossignol
authors.forename: Xavier
authors.initials: X
authors.lastname: Capdevila
mesh_terms: D000244:Adenosine Diphosphate / Q000008:administration & dosage; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000633:toxicity*; D000818:Animals; D002045:Bupivacaine / Q000008:administration & dosage / Q000633:toxicity*; D002950:Citrate (si)-Synthase / Q000187:drug effects / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects; D004734:Energy Metabolism / Q000187:drug effects*; D008297:Male; D008931:Mitochondria, Muscle / Q000187:drug effects* / Q000378:metabolism; D009135:Muscular Diseases / Q000139:chemically induced / Q000503:physiopathology; D010101:Oxygen Consumption / Q000187:drug effects; D011048:Polarography; D016658:Psoas Muscles / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D000779:Anesthetics, Local; D000244:Adenosine Diphosphate; D002950:Citrate (si)-Synthase; D002045:Bupivacaine