Effects of ropivacaine on human neutrophil function: Comparison with bupivacaine and lidocaine

Background and objective: Neutrophils are important both for the immunological defence system and for the inflammatory tissue autoinjury mechanism. However, many local anaesthetics impair certain neutrophil functions. The aim was to assess the effects of ropivacaine, bupivacaine and lidocaine on human neutrophils from adult volunteers. Methods: Chemotaxis, phagocytosis, reactive oxygen species production, intracellular calcium ion ([Ca²⁺]_i) concentrations and protein kinase C activity were measured in the absence and presence of ropivacaine, bupivacaine or lidocaine. The lowest concentrations of the local anaesthetics were similar to those clinically observed in the plasma. Results: Bupivacaine did not affect any neutrophil function (P > 0.05). Ropivacaine failed to change chemotaxis or phagocytosis, while lidocaine suppressed both these neutrophil functions. Ropivacaine (15, 150 μg mL^-1) and lidocaine (20, 200 μg mL^-1) impaired neutrophil production of O₂^-, H₂O₂ and OH^- (P < 0.05) at similar rates (by 7-10%). These same concentrations of ropivacaine and lidocaine suppressed [Ca²⁺]_i elevation. Finally, neither ropivacaine nor bupivacaine inhibited protein kinase C activity, while lidocaine did. Conclusions: Suppression of the [Ca²⁺]_i response in neutrophils by ropivacaine may represent one of the mechanisms responsible for the impairment of neutrophil functions. It should be emphasized that the inhibitory effects of ropivacaine are minor and are attained only at high concentrations, which may minimize the clinical implication of ropivacaine-associated impairment of reactive oxygen species production. Further studies using in vivo systems are required to identify the inhibitory effects of ropivacaine on reactive oxygen species production in clinical settings.