Fig. 3. Caspase activation by lidocaine. Neurons were exposed to 37 mm lidocaine ( A and B ) or 37 mm Tris buffer ( C ) for 30 min, with ( B ) or without ( A and C ) 100 μm z-VAD-fmk and then incubated with sulfo-rhodamine-VAD-fmk for 60 min. ( 1 ) Sulfo-rhodamine fluorescent images, indicating caspase activation; ( 2 ) phase contrast images of the same field; each typical of three experiments; > 7 fields/experiment.