Comparison of the effects of bupivacaine and ropivacaine on heart cell mitochondrial bioenergetics.
BACKGROUND
High lipophilic local anesthetics interfere with mitochondrial energy metabolism. These metabolic effects could in part explain some of the toxic effects of local anesthetics, such as bupivacaine-induced myocardial depression. The aim of this study was to compare the bioenergetic effects of the local anesthetics bupivacaine and ropivacaine.


METHODS
The effects of both local anesthetics on mitochondrial energy metabolism were studied in rat heart isolated mitochondria and in saponin-skinned left ventricle fibers. Oxygen consumption, adenosine triphosphate synthesis, and enzymatic activities of the complexes of the respiratory chain were measured.


RESULTS
Bupivacaine and ropivacaine acted, in isolated mitochondria, as uncouplers between oxygen consumption and phosphorylation of adenosine diphosphate. Further, an inhibitory effect of mitochondrial respiration was evidenced with both anesthetics during maximal respiration and was assigned to a direct inhibition of complex I of the respiratory chain. Mitochondrial adenosine triphosphate synthesis was decreased by both mechanisms. However, both in isolated mitochondria and in permeabilized heart fibers, ropivacaine was less potent than bupivacaine. Adenosine triphosphate synthesis was completely suppressed at 3 mM (approximately 0.1%) bupivacaine, whereas 3 mM ropivacaine induced only about a 40% inhibition.


CONCLUSIONS
Ropivacaine disturbs mitochondrial energy metabolism less than bupivacaine does. The lower lipid solubility of ropivacaine may be responsible for the lesser dose-dependent effects of this drug on mitochondrial bioenergetics.
Sztark
F
F
Laboratoire d'Anesthésiologie (C.J.F. INSERM 9705), Université Victor Segalen Bordeaux 2 and Hôpital Pellegrin, France. Francois.Sztark@graf.u-bordeaux2.fr
Malgat
M
M
Dabadie
P
P
Mazat
J P
JP
D000577:Amides / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D002045:Bupivacaine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D000077212:Ropivacaine
D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D002045:Bupivacaine