Role of potassium channels in Aβ1-40-activated apoptotic pathway in cultured cortical neurons

Potassium channel dysfunction has been implicated in Alzheimer's disease (AD). In the present study, by using potassium channel blocker tetraethylammonium (TEA), we investigated the relationship between the enhancement of potassium currents and the alteration of apoptotic cascade in the neuronal apoptotic model induced by beta‐amyloid peptide 1‐40(Aβ1–40). Cortical neurons exposed to Aβ1–40 5 μM developed a specific increase in the delayed rectifier potassium current (IK), but not the transient outward potassium currents (IA), before the appearance of neuronal apoptosis. Aβ1–40 induced various apoptotic features such as chromatin condensation, a decrease in the amount of Bcl‐2 protein, an increase in the amount of Bax protein, cytochrome c release from mitochondria, and caspase‐3 activation. Potassium channel blocker 5 mM TEA attenuated Aβ1–40‐induced neuronal death and prevented the alterations of all above mentioned apoptotic indicators. The study indicates that IK enhancement might play an important role in certain form of programmed cell death induced by beta‐amyloid peptide (Aβ). Increased potassium channel activity might trigger the activation of apoptosis cascade in Aβ1–40‐treated rat cortical neurons. © 2006 Wiley‐Liss, Inc.