Monitoring transient Ca2+ dynamics with large-conductance Ca2+-dependent K+ channels at active zones in frog saccular hair cells.
Neurotransmitter release from the basolateral surface of auditory and vestibular hair cells is mediated by Ca(2+) influx through voltage-gated Ca(2+) channels. Co-localization of large-conductance Ca(2+)-activated K(+) (BK) channels at the active zones of these cells affords them with an optimal location to act as reporters of the Ca(2+) 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 Ca(2+) concentration during transient influxes of Ca(2+), showing that BK current magnitude and delay to onset are correlated with the rate and duration of Ca(2+) entry through Ca(2+) channels. We also show that BK channels exhibit a much higher Ca(2+) binding affinity in the open state than in the closed state.
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Department of Biology, Mount St Mary's College, Los Angeles, CA 90049, USA.
Grinnell
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AD
Peskoff
A
A
Yazejian
B
B
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D018069:Hair Cells, Vestibular / Q000502:physiology*; D066298:In Vitro Techniques; D042541:Intracellular Space / Q000378:metabolism; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism*; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D011894:Rana pipiens; D012444:Saccule and Utricle / Q000502:physiology*; D013997:Time Factors
D015220:Calcium Channels; D051036:Large-Conductance Calcium-Activated Potassium Channels; D002118:Calcium