Regulation of Neurotransmitter Release by K⁺ Channels

K⁺ channels play potent roles in the process of neurotransmitter release by influencing the action potential waveform and modulating neuronal excitability and release probability. These diverse effects of K⁺ channel activation are ensured by the wide variety of K⁺ channel genes and their differential expression in different cell types. Accordingly, a variety of K⁺ channels have been implicated in regulating neurotransmitter release, including the Ca²⁺- and voltage-gated K⁺ channel Slo1 (also known as BK channel), voltage-gated K⁺ channels of the Kv3 (Shaw-type), Kv1 (Shaker-type), and Kv7 (KCNQ) families, G-protein-gated inwardly rectifying K⁺ (GIRK) channels, and SLO-2 (a Ca²⁺-. Cl⁻, and voltage-gated K⁺ channel in C. elegans). These channels vary in their expression patterns, subcellular localization, and biophysical properties. Their roles in neurotransmitter release may also vary depending on the synapse and physiological or experimental conditions. This chapter summarizes key findings about the roles of K⁺ channels in regulating neurotransmitter release.