title: A switch in the mode of the sodium/calcium exchanger underlies an age-related increase in the slow afterhyperpolarization.
abstract: During aging, the Ca(2+)-sensitive slow afterhyperpolarization (sAHP) of hippocampal neurons is known to increase in duration. This change has also been observed in the serotonergic cerebral giant cells (CGCs) of the pond snail Lymnaea stagnalis, but has yet to be characterized. In this article, we confirm that there is a reduction in firing rate, an increase in the duration of the sAHP, and an alteration in the strength and speed of spike frequency adaptation in the CGCs during aging, a finding that is compatible with an increase in the sAHP current. We go on to show that age-related changes in the kinetics of spike frequency adaptation are consistent with a reduction in Ca(2+) clearance from the cell, which we confirm with Ca(2+) imaging and pharmacological manipulation of the sodium calcium exchanger. These experiments suggest that the sodium calcium exchanger may be switching to a reverse-mode configuration in the CGCs during aging.
authors.affiliation: School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK. Electronic address: g.scutt@brighton.ac.uk.
authors.forename: Greg
authors.initials: G
authors.lastname: Scutt
authors.affiliation: School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK.
authors.forename: Marcus
authors.initials: M
authors.lastname: Allen
authors.affiliation: Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton, UK.
authors.forename: György
authors.initials: G
authors.lastname: Kemenes
authors.affiliation: School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Yeoman
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000375:Aging / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002490:Central Nervous System / Q000166:cytology; D008195:Lymnaea; D018408:Patch-Clamp Techniques; D059326:Serotonergic Neurons / Q000378:metabolism / Q000502:physiology*; D019831:Sodium-Calcium Exchanger / Q000502:physiology*
chemical_list: D019831:Sodium-Calcium Exchanger; D002118:Calcium
keywords: Aging; Cerebral giant cells; Lymnaea stagnalis; NCX; Slow afterhyperpolarization; Sodium calcium exchanger