Paradoxical Role of Large-Conductance Calcium-Activated K + (BK) Channels in Controlling Action Potential-Driven Ca 2+ Entry in Anterior Pituitary Cells
2001; Society for Neuroscience; Volume: 21; Issue: 16 Linguagem: Inglês
10.1523/jneurosci.21-16-05902.2001
ISSN1529-2401
AutoresFredrick Van Goor, Yuexian Li, Stanko S. Stojilković,
Tópico(s)Cardiac electrophysiology and arrhythmias
ResumoActivation of high-conductance Ca(2+)-activated K(+) (BK) channels normally limits action potential duration and the associated voltage-gated Ca(2+) entry by facilitating membrane repolarization. Here we report that BK channel activation in rat pituitary somatotrophs prolongs membrane depolarization, leading to the generation of plateau-bursting activity and facilitated Ca(2+) entry. Such a paradoxical role of BK channels is determined by their rapid activation by domain Ca(2+), which truncates the action potential amplitude and thereby limits the participation of delayed rectifying K(+) channels during membrane repolarization. Conversely, pituitary gonadotrophs express relatively few BK channels and fire single spikes with a low capacity to promote Ca(2+) entry, whereas an elevation in BK current expression in a gonadotroph model system leads to the generation of plateau-bursting activity and high-amplitude Ca(2+) transients.
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