The mechanism of neuroprotection by positive modulation of Ca2+-activated K+ channels of cerebellar neurons in primary culture
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Here we show that positive modulators (CyPPA and NS309) of Ca2+-activated K+ channels of small (SK) and intermediate (IK) conductances in cerebellar neurons decrease glutamate-evoked Ca2+ entry into neurons independently on the presence of Mg2+ in extracellular media. An analysis of neuronal viability after long-term (240 min) glutamate treatments demonstrated neuroprotective action of CyPPA and NS309. Extracellular Mg2+ did not protect neurons from apoptosis during prolonged treatment with glutamate. Activation of SK and IK channels results in local membrane hyperpolarization, which enhances Mg2+ block of NMDA receptors and reduces activation of voltage-dependent Ca2+ channels, which can explain neuroprotection caused by CyPPA or NS309. The obtained results reveal an important role Ca2+-activated K+ channels of small and intermediate conductance in the regulation of Ca2+ entry into cerebellar neurons via NMDA receptors and voltage-gated Ca2+ channels.
Keywordsprimary culture neurons cerebellum SK channels calcium
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