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Properties and physiological function of Ca 2+ -dependent K + currents in uniglomerular olfactory projection neurons

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journal contribution
posted on 26.04.2019, 15:23 by C Bradler, B Warren, V Bardos, S Schleicher, A Klein, P Kloppenburg
Ca2+-activated potassium currents [IK(Ca)] are an important link between the intracellular signaling system and the membrane potential, which shapes intrinsic electrophysiological properties. To better understand the ionic mechanisms that mediate intrinsic firing properties of olfactory uniglomerular projection neurons (uPNs), we used whole cell patch-clamp recordings in an intact adult brain preparation of the male cockroach Periplaneta americana to analyze IK(Ca). In the insect brain, uPNs form the principal pathway from the antennal lobe to the protocerebrum, where centers for multimodal sensory processing and learning are located. In uPNs the activation of IK(Ca) was clearly voltage and Ca2+ dependent. Thus under physiological conditions IK(Ca) is strongly dependent on Ca2+ influx kinetics and on the membrane potential. The biophysical characterization suggests that IK(Ca) is generated by big-conductance (BK) channels. A small-conductance (SK) channel-generated current could not be detected. IK(Ca) was sensitive to charybdotoxin (CTX) and iberiotoxin (IbTX) but not to apamin. The functional role of IK(Ca) was analyzed in occlusion experiments under current clamp, in which portions of IK(Ca) were blocked by CTX or IbTX. Blockade of IK(Ca) showed that IK(Ca) contributes significantly to intrinsic electrophysiological properties such as the action potential waveform and membrane excitability.

Funding

This work was supported by grant KL 762/5-1 from the Deutsche Forschungsgemeinschaft, a CONNECT grant, and a Max-Delbrück Award from the University of Cologne to P. Kloppenburg, and an Alexander von Humboldt fellowship awarded to B. Warren.

History

Citation

Journal of Neurophysiology, 2016, 115 (5), pp. 2330-2340

Author affiliation

/Organisation/COLLEGE OF LIFE SCIENCES/Biological Sciences/Neuroscience, Psychology and Behaviour

Version

AM (Accepted Manuscript)

Published in

Journal of Neurophysiology

Publisher

American Physiological Society

issn

0022-3077

eissn

1522-1598

Acceptance date

27/01/2016

Copyright date

2016

Available date

26/04/2019

Publisher version

https://www.physiology.org/doi/full/10.1152/jn.00840.2015

Language

en