Abstract
Release of neurotransmitter at the inner hair cell (IHC) afferent synapse is a fundamental step in translating sound into auditory nerve excitation. To study the Ca 2+ dependence of the underlying vesicle fusion and subsequent endocytosis, we combined Ca 2+ uncaging with membrane capacitance measurements in mouse IHCs. Rapid elevations in [Ca 2+] i above 8 μM caused a biphasic capacitance increase corresponding to the fusion of ∼40,000 vesicles. The kinetics of exocytosis displayed a fifth-order Ca 2+ dependence reaching maximal rates of >3 × 10 7 vesicle/s. Exocytosis was always followed by slow, compensatory endocytosis (τ ≅ 15 s). Higher [Ca 2+] i increased the contribution of a faster mode of endocytosis with a Ca 2+-independent time constant of ∼300 ms. These properties provide for rapid and sustained transmitter release from this large presynaptic terminal.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
