SK channels in excitability, pacemaking and synaptic integration

Small conductance calcium-activated potassium channels link elevations of intracellular calcium ions to membrane potential, exerting a hyperpolarizing influence when activated. The consequences of SK channel activity have been revealed by the specific blocker apamin, a peptide toxin from honeybee venom. Recent studies have revealed unexpected roles for SK channels in fine-tuning intrinsic cell firing properties and in responsiveness to synaptic input. They have also identified specific roles for different SK channel subtypes. A host of Ca²⁺ sources, including distinct subtypes of voltage-dependent calcium channels, intracellular Ca²⁺ stores and Ca ²⁺-permeable ionotropic neurotransmitter receptors, activate SK channels. The macromolecular complex in which the Ca²⁺ source, SK channels and various modulators are assembled determines the kinetics and consequences of SK channel activation.