Prevention of NO-induced intracellular proteolysis by caspase inhibitors
(A) CGC were incubated with 150 µM GSNO and DEVD-afc cleavage activity was determined in cell lysates (in the absence or presence of 1 µM z-D-cbk) after the time points indicated. Data are means ± SD of triplicate determinations. (B) CGC were preincubated for 30 min with 2 µM MK801, 100 µM z-D-cbk, z-VAD-fmk, z-DEVD-fmk, Ac-YVAD-cmk, 1 mM DEVD-CHO, 100 µM z-F-cmk, or solvent control only. Then they were challenged with 200 µM GSNO. Colchicine (1 µM; 12 hr) was used as positive control for induction of CGC apoptosis. After 4 hr, cells were lysed and fodrin proteolysis was determined by immunoblot. Less than 5% of CGC had lost membrane permeability at that time point.