Fig. 6. Tetracaine-induced caspase-3 activation. PC12 cells were treated with 1 mm tetracaine for indicated times. Proteins (50 μg) were subjected to sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Cleavage of proform of caspase-3 and poly(adenosine diphosphate–ribose) polymerase (PARP) was determined. Special bands are indicated by arrows on the left. Caspase-3 proform breakdown (A ) and cleavage of PARP (B ) were detected after 4 h of tetracaine treatment. An 89-kd signature fragment of PARP was clearly observed at 8 h (B ).