Monitoring transient Ca2+ dynamics with large-conductance Ca2+ -dependent K+ channels at active zones in frog saccular hair cells

• Published in: Neuroscience 2010-02, Vol.165 (3), p.715-722
• Main Authors: Sy, T, Grinnell, A.D, Peskoff, A, Yazejian, B
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Calcium - metabolism; Calcium Channels - metabolism; Fundamental and applied biological sciences. Psychology; Hair Cells, Vestibular - physiology; In Vitro Techniques; Intracellular Space - metabolism; Large-Conductance Calcium-Activated Potassium Channels - metabolism; Membrane Potentials; Neurology; Patch-Clamp Techniques; Rana pipiens; Saccule and Utricle - physiology; Time Factors; Vertebrates: nervous system and sense organs
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2009.11.003

Abstract Neurotransmitter release from the basolateral surface of auditory and vestibular hair cells is mediated by Ca2+ influx through voltage-gated Ca2+ channels. Co-localization of large-conductance Ca2+ -activated K+ (BK) channels at the active zones of these cells affords them with an optimal location to act as reporters of the Ca2+ concentration changes at active zones of transmitter release. In this report we use BK channels in frog ( Rana pipiens ) hair cells to monitor dynamic changes in intracellular Ca2+ concentration during transient influxes of Ca2+ , showing that BK current magnitude and delay to onset are correlated with the rate and duration of Ca2+ entry through Ca2+ channels. We also show that BK channels exhibit a much higher Ca2+ binding affinity in the open state than in the closed state.