Effects of bupivacaine on human erythrocytes submitted to stress and evidence for an interaction between bupivacaine and flumazenil

Aims To examine the effects of bupivacaine on erythrocytes submitted to an oxidative stress (AAPH) and to provide evidence for an in vitro interaction between bupivacaine and flumazenil. Methods Human erythrocytes were studied with or without AAPH in the presenc e of different concentrations of bupivacaine (0.15, 0.3, 0.9 and 1.8 mmol l (-1) ), or flumazenil (0.16 mmol l(-1) ) and with the association of flumaz enil and two doses of bupivacaine (0.15 and 0.3 mmol l(-1) ). Potassium eff lux was measured by flame photometry at t(0), and every 30 min for 2 h. Results In the absence of AAPH, extracellular potassium remained unchanged. Oxidative stress induced a significant increase in extracellular potassium , which was not modified by incubation with flumazenil. Bupivacaine signifi cantly lowered the increase in extracellular potassium in a dose-related fa shion. The association with flumazenil blunted the effects of bupivacaine. Discussion In this model, bupivacaine proved effective in protecting erythr ocytes against oxidative stress. Flumazenil interacted with bupivacaine and blunted its protective effects.