Comparison of myotoxic effects of levobupivacaine, bupivacaine and ropivacaine: apoptotic activity and acute effect on pro-inflammatory cytokines.

We investigated the myotoxic effects of bupivacaine, ropivacaine and levobupivacaine on rat skeletal muscle and compared its apoptotic activity and acute effects on pro-nflammatory cytokines. We divided 40 Wistar albino rats into four equal groups. Rats were injected intramuscularly with 0.5% bupivacaine (group B), 0.5% ropivacaine (group R), 0.5% levobupivacaine (group L) or 0.9% normal saline (group SF). Animals were sacrificed on the second day after the injection. TNF-α, IL-1 and IL-6 levels were examined in muscle tissue using immunohistochemistry and immunofluorescence. Apoptotic cells were visualized by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. We found that levobupivacaine caused the lowest TNF-α, IL-1 and IL-6 expression levels, while the bupivacaine group caused the highest level compared to the other two agents. The greatest number of apoptotic cells was found in the bupivacaine group. Bupivacaine was more myotoxic than other anesthetic agents and increased apoptosis. The number of TUNEL positive apoptotic cells was lowest in the SF group. The greatest IL-1 immunoreactivity was found in the bupivacaine group. Bupivacaine and ropivacaine produced greater IL-6 expression than the SF group. Bupivacaine and ropivacaine caused greater TNF-α expression than the SF group, whereas the immunoreactivity of TNF-α was similar in the bupivacaine and ropivacaine groups.