Figure 4.

Activation of Cx43 hemichannel in cultured cortical astrocytes is Ca²⁺ dependent. A1–A3, Fluorescent images of EtBr uptake in cultured astrocytes in control condition (CTL), after treatment with ionomycin (1 μm), and after treatment with ionomycin plus CBX (50 μm). Scale bar, 5 μm. Note that, whereas in control conditions, the uptake of EtBr was not observed (A1), it became detected in the presence of the Ca²⁺ ionophore ionomycin (1 μm; A2) and was prevented by adding CBX to ionomycin (A3). B, Time-dependent increase in resting [Ca²⁺]_i recorded in astrocytes loaded with Fluo-4/AM and treated with ionomycin. Error bars indicate mean ± SD, n > 100 astrocytes for the same experiment. C, Histogram showing EtBr uptake expressed as the mean fluorescence intensity per astrocyte nucleus in control and after treatment with ionomycin. The increase in EtBr uptake triggered by ionomycin was blocked by either CBX (50 μm) or Gap26 (100 μm; p < 0.05, Student's t test, n = 3 independent cultures).