Kv3.1-Kv3.2 channels underlie a high-voltage-activating component of the delayed rectifier K+ current in projecting neurons from the globus pallidus
Por:
Hernández-Pineda R., Chow A., Amarillo Y., Moreno H., Saganich M., Vega-Saenz De Miera E., Hernández-Cruz A., Rudy B.
Publicada:
1 ene 1999
Resumen:
The globus pallidus plays central roles in the basal ganglia circuitry involved in movement control as well as in cognitive and emotional functions. There is therefore great interest in the anatomic and electrophysiological characterization of this nucleus. Most pallidal neurons are GABAergic projecting cells, a large fraction of which express the calcium binding protein parvalbumin (PV). Here we show that PV-containing pallidal neurons coexpress Kv3.1 and Kv3.2 K+ channel proteins and that both Kv3.1 and Kv3.2 antibodies coprecipitate both channel proteins from pallidal membrane extracts solubilized with nondenaturing detergents, suggesting that the two channel subunits are forming heteromeric channels. Kv3.1 and Kv3.2 channels have several unusual electrophysiological properties when expressed in heterologous expression systems and are thought to play special roles in neuronal excitability including facilitating sustained high-frequency firing in fast-spiking neurons such as interneurons in the cortex and the hippocampus. Electrophysiological analysis of freshly dissociated pallidal neurons demonstrates that these cells have a current that is nearly identical to the currents expressed by Kv3.1 and Kv3.2 proteins in heterologous expression systems, including activation at very depolarized membrane potentials (more positive than - 10 mV) and very fast deactivation rates. These results suggest that the electrophysiological properties of native channels containing Kv3.1 and Kv3.2 proteins in pallidal neurons are not significantly affected by factors such as associated subunits or postranslational modifications that result in channels having different properties in heterologous expression systems and native neurons. Most neurons in the globus pallidus have been reported to fire sustained trains of action potentials at high-frequency. Kv3.1-Kv3.2 voltage-gated K+ channels may play a role in helping maintain sustained high-frequency repetitive firing as they probably do in other neurons.
Filiaciones:
Hernández-Pineda R.:
Dept. of Physiology and Neuroscience, New York Univ. School of Medicine, New York City, NY 10016, United States
Inst. de Fisiología Celular, Univ. Nac. Auton. de México, Mexico City 04510, Mexico
Chow A.:
Dept. of Physiology and Neuroscience, New York Univ. School of Medicine, New York City, NY 10016, United States
Amarillo Y.:
Dept. of Physiology and Neuroscience, New York Univ. School of Medicine, New York City, NY 10016, United States
Moreno H.:
Dept. of Physiology and Neuroscience, New York Univ. School of Medicine, New York City, NY 10016, United States
Saganich M.:
Dept. of Physiology and Neuroscience, New York Univ. School of Medicine, New York City, NY 10016, United States
Vega-Saenz De Miera E.:
Dept. of Physiology and Neuroscience, New York Univ. School of Medicine, New York City, NY 10016, United States
Hernández-Cruz A.:
Inst. de Fisiología Celular, Univ. Nac. Auton. de México, Mexico City 04510, Mexico
Rudy B.:
Dept. of Physiology and Neuroscience, New York Univ. School of Medicine, New York City, NY 10016, United States
Dept. of Physiology and Neuroscience, New York Univ. School of Medicine, 550 First Ave., New York City, NY 10016, United States
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