Figure 2. siRNA knock down of endogenous Cx43 sensitizes cultured primary astrocytes to H₂O₂-induced apoptosis.

A. Cultured primary astrocytes were transfected with Cx43 siRNA (left) or control siRNA (right) (200 pmoles/ well) and the level of Cx43 protein in cell lysates harvested at the indicated time points after transfection determined by a Western blot. The blot shown is representative of 3 replicate experiments. GAPDH serves as a loading control. B. Photographs of control C6 cells with or without H₂O₂ treatment. Note the clear correlation between cells with nuclear condensation (arrows) and the TUNEL positive cells. Scale bar = 30 μm. C. 48 h after siRNA transfection, cultures were treated with H₂O₂ (0, 300, or 1000 μM) for 24h and subsequently fixed. Hoechst stained nuclei were counted from random fields and apoptotic nuclei expressed as a percentage of total. Data represent mean ± SD from four independent experiments. * denotes p<0.05 or ** p <0.01 between the control (open) and 200 pmoles siRNA transfected (hatched) conditions.