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This Article Full Text Full Text (PDF) Supplemental data All Versions of this Article: 579/3/737    most recent jphysiol.2006.122564v3 jphysiol.2006.122564v2 jphysiol.2006.122564v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schaefer, A. T. Articles by Korngreen, A. Search for Related Content PubMed PubMed Citation Articles by Schaefer, A. T. Articles by Korngreen, A. Related Collections Neuroscience

¹ Abteilung Zellphysiologie, Max-Planck Institut für Medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
² The Leslie and Susan Gonda Interdisciplinary Brain Research Center
³ The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel

Voltage-gated potassium channels effectively regulate dendritic excitability in neurones. It has been suggested that in the distal apical dendrite of layer 5B (L5B) neocortical pyramidal neurones, K⁺ conductances participate in active dendritic synaptic integration and control regenerative dendritic potentials. The ionic mechanism for triggering these regenerative potentials has yet to be elucidated. Here we used two-electrode voltage clamp (TEVC) to quantitatively record K⁺ conductance densities of a sustained K⁺ conductance in the soma and apical dendrite of L5B neurones of adult rats. We report that the somatic and proximal dendritic sustained voltage-gated K⁺ conductance density is more than 10-fold larger than previous estimates. The results obtained using TEVC were corroborated using current-clamp experiments in combination with compartmental modelling. Possible error sources, including inaccurate measurement of the passive membrane parameters and unknown axonal and basal dendritic conductance distributions, were shown not to distort the density estimation considerably. The sustained voltage-gated K⁺ conductance density was found to decrease steeply along the apical dendrite. The steep negative K⁺ conductance density gradient along the apical dendrite may help to define a distal, low-threshold region for amplification of distal synaptic input in L5B pyramidal neurones.

(Received 15 November 2006; accepted after revision 6 December 2006; first published online 14 December 2006)
Corresponding author A. Korngreen: Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel. Email: korngra{at}mail.biu.ac.il

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