Referenced in: none

Automatically associated channels: Kv3.1 , Kv3.4 , Slo1

Title: Kv3-like potassium channels are required for sustained high-frequency firing in basal ganglia output neurons.

Authors: Shengyuan Ding, Shannon G Matta, Fu-Ming Zhou

Journal, date & volume: J. Neurophysiol., 2011 Feb , 105, 554-70

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/21160004

Abstract
The GABA projection neurons in the substantial nigra pars reticulata (SNr) are key output neurons of the basal ganglia motor control circuit. These neurons fire sustained high-frequency, short-duration spikes that provide a tonic inhibition to their targets and are critical to movement control. We hypothesized that a robust voltage-activated K(+) conductance that activates quickly and resists inactivation is essential to the remarkable fast-spiking capability in these neurons. Semi-quantitative RT-PCR (qRT-PCR) analysis on laser capture-microdissected nigral neurons indicated that mRNAs for Kv3.1 and Kv3.4, two key subunits for forming high activation threshold, fast-activating, slow-inactivating, 1 mM tetraethylammonium (TEA)-sensitive, fast delayed rectifier (I(DR-fast)) type Kv channels, are more abundant in fast-spiking SNr GABA neurons than in slow-spiking nigral dopamine neurons. Nucleated patch clamp recordings showed that SNr GABA neurons have a strong Kv3-like I(DR-fast) current sensitive to 1 mM TEA that activates quickly at depolarized membrane potentials and is resistant to inactivation. I(DR-fast) is smaller in nigral dopamine neurons. Pharmacological blockade of I(DR-fast) by 1 mM TEA impaired the high-frequency firing capability in SNr GABA neurons. Taken together, these results indicate that Kv3-like channels mediating fast-activating, inactivation-resistant I(DR-fast) current are critical to the sustained high-frequency firing in SNr GABA projection neurons and hence movement control.