title: Comparison of the effects of mepivacaine and lidocaine on rat myocardium.
abstract: OBJECTIVE
  To compare the inotropic and lusitropic effect of lidocaine and mepivacaine on rat papillary muscle.
  
  
  METHODS
  Effects of lidocaine and mepivacaine (10-8-10-3 M) were studied in rat left ventricular papillary muscles in vitro at a calcium concentration of 1 mmol, under low (isotony) and high (isometric) loads.
  
  
  RESULTS
  Lidocaine induced a significant negative inotropic effect in isotonic and isometric conditions whereas mepivacaine did not. Mepivacaine only induced a negative inotropic effect when added as a bolus for the highest concentration and this effect was significantly more pronounced with lidocaine than with mepivacaine (active force at 10-3 M: 63 +/- 10 vs. 84 +/- 10% of baseline, P < 0.05). Increasing calcium concentration resulted in a greater positive inotropic effect in the control (199 +/- 11% of baseline) and mepivacaine groups (197 +/- 22% of baseline) when compared to the lidocaine group (163 +/- 19% of baseline, P < 0.05 vs. lidocaine and control groups), suggesting an impairment on intracellular Ca2+ handling by lidocaine. A negative lusitropic effect under low load was observed only for mepivacaine and suggested an impairment of sarcoplasmic reticulum function. Lidocaine and mepivacaine did not modify post-rest potentiation but significantly depressed the force-frequency relationship.
  
  
  CONCLUSIONS
  The negative inotropic and lusitropic effects induced by lidocaine were more important than that of mepivacaine and may involve an impairment of intracellular Ca2+ handling.
authors.affiliation: Laboratoire d'Anesthésiologie, Equipe d'Accueil 1896, Département d'Anesthésie-Réanimation-SAMU, CHU Edouard Herriot, Hospices Civils de Lyon, Université Claude Bernard, 3 Place d'Arsonval, 69437 Lyon Cedex 03, France. js-david@univ-lyon1.fr
authors.forename: J-S
authors.initials: JS
authors.lastname: David
authors.forename: J
authors.initials: J
authors.lastname: Amour
authors.forename: C
authors.initials: C
authors.lastname: Duracher
authors.forename: C
authors.initials: C
authors.lastname: Ferretti
authors.forename: P
authors.initials: P
authors.lastname: Precloux
authors.forename: P
authors.initials: P
authors.lastname: Petit
authors.forename: B
authors.initials: B
authors.lastname: Riou
authors.forename: P-Y
authors.initials: PY
authors.lastname: Gueugniaud
mesh_terms: D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D017610:Calcium Compounds / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D008012:Lidocaine / Q000494:pharmacology*; D008297:Male; D008619:Mepivacaine / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000779:Anesthetics, Local; D017610:Calcium Compounds; D008012:Lidocaine; D008619:Mepivacaine