Clinical dose of lidocaine destroys the cell membrane and induces both necrosis and apoptosis in an identified Lymnaea neuron

Purpose Although lidocaine-induced cell toxicity has been reported, its mechanism is unclear. Cell size, morphological change, and membrane resistance are related to homeostasis and damage to the cell membrane; however, the effects of lidocaine on these factors are unclear. Using an identified LPeD1 neuron from Lymnaea stagnalis , we sought to determine how lidocaine affects these factors and how lidocaine is related to damage of the cell membrane. Methods Cell size and morphological form were measured by a micrograph and imaging analysis system. Membrane potential and survival rate were obtained by intracellular recording. Membrane resistance and capacitance were measured by whole-cell patch clamp. Phosphatidyl serine and nucleic acid were double stained and simultaneously measured by annexin V and propidium iodide. Results Lidocaine at a clinical dose (5–20 mM) induced morphological change (bulla and bleb) in the neuron and increased cell size in a concentration-dependent manner. Membrane potential was depolarized in a concentration-dependent manner. At perfusion of more than 5 mM lidocaine, the depolarized membrane potential was irreversible. Lidocaine decreased membrane resistance and increased membrane capacitance in a concentration-dependent manner. Both phosphatidyl serine and nucleic acid were stained under lidocaine exposure in a concentration-dependent manner. Conclusions A clinical dose of lidocaine greater than 5 mM destroys the cell membrane and induces both necrosis and apoptosis in an identified Lymnaea neuron.