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J Physiol. 2004 Aug 15;559(Pt 1):187-203. Epub 2004 Jun 24.

Properties of single voltage-dependent K+ channels in dendrites of CA1 pyramidal neurones of rat hippocampus.

Author information

1
Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA. xixi@ltp.neusc.bcm.tmc.edu

Abstract

Voltage-dependent K(+) channels in the apical dendrites of CA1 pyramidal neurones play important roles in regulating dendritic excitability, synaptic integration, and synaptic plasticity. Using cell-attached, voltage-clamp recordings, we found a large variability in the waveforms of macroscopic K(+) currents in the dendrites. With single-channel analysis, however, we were able to identify four types of voltage-dependent K(+) channels and we categorized them as belonging to delayed-rectifier, M-, D-, or A-type K(+) channels previously described from whole-cell recordings. Delayed-rectifier-type K(+) channels had a single-channel conductance of 19 +/- 0.5 pS, and made up the majority of the sustained K(+) current uniformly distributed along the apical dendrites. The M-type K(+) channels had a single-channel conductance of 11 +/- 0.8 pS, did not inactivate with prolonged membrane depolarization, deactivated with slow kinetics (time constant 100 +/- 6 ms at -40 mV), and were inhibited by bath-applied muscarinic agonist carbachol (10 microm). The D-type K(+) channels had a single-channel conductance of around 18 pS, and inactivated with a time constant of 98 +/- 4 ms at +54 mV. The A-type K(+) channels had a single-channel conductance of 6 +/- 0.6 pS, inactivated with a time constant of 23 +/- 2 ms at +54 mV, and contributed to the majority of the transient K(+) current previously described. These results suggest both functional and molecular complexity for K(+) channels in dendrites of CA1 pyramidal neurones.

PMID:
15218076
PMCID:
PMC1665081
DOI:
10.1113/jphysiol.2004.068114
[Indexed for MEDLINE]
Free PMC Article

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