Figure 3.

Glioma cells express Ca²⁺-activated K⁺ channels. (A) Representative recordings from glioma cells in a brain section or isolated cell. Outward currents were sensitive to paxilline, a specific inhibitor of Ca²⁺-activated K⁺ channels. Block was incomplete in brain slices because drug perfusion was limited in tissue. (B) Application of Acetylcholin (Ach) to a cultured glioma cell recorded using amphotericin perforated patch, hence without disturbing intracellular Ca²⁺ caused a rapid increase in Ca²⁺ determined by Fura-II recording (top) associated with a large hyperpolarizing voltage shift indicating activation of BK channels. (C) Two biopsies each from patients with gliomas ranging in malignancy grade from WHO-I-IV show an increase in BK channel protein with increasing malignancy on Western blot. [(C) reproduced with permission from (23); (B) reproduced with permission from (25).]