Fig. 6.

Cytokines induce caspase-3 activation in RINm5F cells and rat islets. RINm5F cells (2.0 × 10⁵ cells/400 μl RPMI; A) or rat islets (150 islets/400 μl CMRL; B and C) were treated with IL-1 (10 U/ml) for 24 (black bars) or 36 h (open bars), followed by the addition of l-NMMA and continued culture for an additional 8 or 18 h in the presence of both the NOS inhibitor and cytokine, as indicated. A and B: the cells and islets were harvested, and caspase-3 activity was determined. A also provides a control in which RINm5F cells were coincubated with IL-1 and l-NMMA for 36 h. C: following a 36-h IL-1 treatment or 36 h with IL-1 followed by the addition of l-NMMA and continued incubation for 24 h, the islets were dispersed and the cells centrifuged onto slides. The presence of active caspase-3 was examined by immunohistochemistry using antibodies specific for cleaved caspase-3 (red), insulin (green), and 4′,6-diamidino-2-phenylindole (DAPI; blue). Results are the average ± SE of at least 3 independent experiments. Statistically significant increases in caspase-3 activity compared with untreated controls are as indicated (*P < 0.05).