Activation kinetics of the slow afterhyperpolarization in hippocampal CA1 neurons

Aaron C. Gerlach, James Maylie, John P. Adelman

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

The activation of the slow afterhyperpolarization (sAHP) in CA1 neurons was studied using whole-cell recordings in the presence of inhibitors of the fast and medium-duration AHPs. The amplitude of the slow afterhyperpolarization current (IsAHP) increased as a function of duration and magnitude of the depolarizing voltage pulse reflecting graded increases in Ca2+ influx through voltage-dependent Ca2+ channels. Therefore, the time constant for activation, τmax, determined from a family of IsAHPs as a function of pulse duration, was voltage dependent decreasing several-fold within the range of-20 to 20 mV and was dependent on extracellular [Ca 2+]. The IsAHP displayed a pronounced rising phase that was well fit by a single exponential with a time constant, τrise, that was invariant of pulse duration, voltage, IsAHP amplitude, or external [Ca 2+] and was significantly slower than the τmax. In current clamp, the magnitude of the sAHP increased with the number of evoked action potentials, yet τrise of the sAHP was invariant of action potential number and was similar to the τrise of the IsAHP recorded in voltage-clamp. The results suggest that there are two components to the development of the IsAHP, a rapid, voltage- and Ca2+-dependent step, the magnitude and rate of which reflects the voltage dependence of the Ca2+ channels, that triggers a second rate-limiting, voltage-independent process that dictates the slow IsAHP rise kinetics.

Original languageEnglish (US)
Pages (from-to)187-196
Number of pages10
JournalPflugers Archiv European Journal of Physiology
Volume448
Issue number2
DOIs
StatePublished - May 1 2004

Keywords

  • Afterhyperpolarization
  • CA1
  • Calcium-dependent potassium channel
  • Channel activation
  • Slow afterhyperpolarization
  • Spike frequency adaptation

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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