A, caspase-3 activity was measured in cells 16 h after treatment with 5 μm rotenone (Rot). Where indicated, cells were pretreated for 30 min with 300 μm oxotremorine-M (Oxo), 300 μm carbachol (Cb), or 10 μm nicotine (Nic). Cells were treated with the antagonists 10 μm atropine (Atr) or 10 μm mecamylamine (Mec) 15 min before treatment with agonists. Values are presented as the percent of caspase-3 activity in untreated control (Ctl) cells and are the means ±S.E.; n = 3–4; *, p < 0.05 compared with values from samples treated with rotenone alone. B, caspase-3 activity was measured in cells treated with 0.5 μm staurosporine alone or after a 30-min pretreatment with 300 μm oxotremorine-M. Values are presented as the percent of caspase-3 activity in untreated control cells (means ±S.E.; n = 3).