Presynaptic External Calcium Signaling Involves the Calcium-Sensing Receptor in Neocortical Nerve Terminals

摘要

BackgroundNerve terminal invasion by an axonal spike activates voltage-gated channels, triggering calcium entry, vesicle fusion, and release of neurotransmitter. Ion channels activated at the terminal shape the presynaptic spike and so regulate the magnitude and duration of calcium entry. Consequently characterization of the functional properties of ion channels at nerve terminals is crucial to understand the regulation of transmitter release. Direct recordings from small neocortical nerve terminals have revealed that external [Ca²⁺] ([Ca²⁺]o) indirectly regulates a non-selective cation channel (NSCC) in neocortical nerve terminals via an unknown [Ca²⁺]o sensor. Here, we identify the first component in a presynaptic calcium signaling pathway.