Fig. 7. Caspase-8 and -9 activities. After correction of background activity and number of cells, enzymatic activity was expressed as percent increase in activity over control cells. (A ) Caspase-9 activity. Norepinephrine (NE) induced a significant increase in caspase-9 activity, which was inhibited by treatment with diltiazem (DIL; 1 μm), propranolol (PRO; 2 μm), isoflurane (ISO; 1.6 MAC), and halothane (HAL; 1.2 MAC). Data are mean ± SD. *P < 0.0001 versus  control (CTL), †not significant versus  CTL. (B ) Caspase-8 activity. Caspase-8 was not activated in NE-treated cultures.