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Neurobiol Aging. 2015 Jun;36(6):2176-83. doi: 10.1016/j.neurobiolaging.2014.12.040. Epub 2015 Jan 31.

Age-related changes in large-conductance calcium-activated potassium channels in mammalian circadian clock neurons.

Author information

1
Laboratory of Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
2
Laboratory of Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands. Electronic address: s.michel@lumc.nl.

Abstract

Aging impairs the function of the suprachiasmatic nucleus (SCN, the central mammalian clock), leading to a decline in the circadian rhythm of many physiological processes, including sleep-wake rhythms. Recent studies have found evidence of age-related changes in the circadian regulation of potassium currents; these changes presumably lead to a decrease in the SCN's electrical rhythm amplitude. Current through large-conductance Ca(2+)-activated K(+) (BK) channels promote rhythmicity in both SCN neuronal activity and behavior. In many neuron types, changes in BK activity are correlated with changes in intracellular Ca(2+) concentration ([Ca(2+)]i). We performed patch-clamp recordings of SCN neurons in aged mice and observed that the circadian modulation of BK channel activity was lost because of a reduction in BK currents during the night. This reduced current diminished the afterhyperpolarization, depolarized the resting membrane potential, widened the action potential, and increased [Ca(2+)]i. These data suggest that reduced BK current increases [Ca(2+)]i by altering the action potential waveform, possibly contributing to the observed age-related phenotype.

KEYWORDS:

Action potential; Afterhyperpolarization; Aging; Calcium; Potassium channels; Suprachiasmatic nucleus

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