Figure 7.

Conditioned medium harvested from activated microglia induces unitary current events of Cx43 hemichannels in cortical astrocytes. a, Voltage ramps from −80 to 0 mV, 3 s in duration, were applied. The ramp was initiated by a transition from 0 to −80 mV. b, c, Currents of control and CM*-treated astrocytes for 24 h, respectively. b, d, Under control conditions, no hemichannel openings were observed, and EthBr uptake was low. c, d, In astrocytes treated for 24 h with CM*, hemichannel openings were clearly observed, and this cell showed close to twice the amount of EthBr uptake compared with cells under control conditions. The boxed region in d is shown as conductance at the right bottom where two hemichannels of ∼220 pS each show transitions between closed to open states. Tilted traced along both closed, one open, and both open indicate the progressive changes in voltage during the ramp application. d, In CM*-treated astrocytes, the EthBr uptake fraction sensitive to La³⁺ (200 μm) was bigger than in control cells, indicating that more hemichannels were open in CM*-treated cells.