Blockade of KCa3.1 channels inhibits astrocyte proliferation. Cells were trypsinized and seeded for 48 h, then treated for 96 h with or without TRAM-34 (1-30 μM) in culture medium. Cell proliferation was then measured as described in Materials and Methods. After treating cells with serum-free medium for 24 h, proliferation was induced by 10% FBS in the absence or presence of TRAM-34 (1, 10 and 20 μM) for 96 h, and then assayed by measuring Ki67 (A, B) or counting cells (C) at the indicated times (n = 4). Data are presented as means ± SEM. ** p < 0.01 versus control.