 |
||||
|
||||
|
||||
|
||||
|
||||
The Journal of Neuroscience, May 25, 2005, 25(21):5159-5170; doi:10.1523/JNEUROSCI.4238-04.2005
Previous Article | Next Article
Behavioral/Systems/Cognitive
Sodium Currents in Medullary Neurons Isolated from the Pre-Bötzinger Complex Region
Krzysztof Ptak, Greer G. Zummo, George F. Alheid, Tatiana Tkatch, D. James Surmeier, andDonald R. McCrimmon Department of Physiology and Institute for Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611-3008
The pre-Bötzinger complex (preBötC) in the ventrolateral medulla contains interneurons important for respiratory rhythm generation. Voltage-dependent sodium channels mediate transient current (INaT), underlying action potentials, and persistent current (INaP), contributing to repetitive firing, pacemaker properties, and the amplification of synaptic inputs. Voltage-clamp studies of the biophysical properties of these sodium currents were conducted on acutely dissociated preBötC region neurons. Reverse transcription-PCR demonstrated the presence of mRNA for Nav1.1, Nav1.2, and Nav1.6
-subunits in individual neurons. A TTX-sensitive INaP was evoked in all tested neurons by ramp depolarization from -80 to 0 mV. Including a constant in the Boltzmann equation for inactivation by estimating the steady-state fraction of Na+ channels available for inactivation allowed prediction of a window current that did not decay to 0 at voltages positive to -20 mV and closely matched the measured INaP. Riluzole (3 µM), a putative INaP antagonist, reduced both INaP and INaT and produced a hyperpolarizing shift in the voltage dependence of steady-state inactivation. The latter decreased the predicted window current by an amount equivalent to the decrease in INaP. Riluzole also decreased the inactivation time constant at potentials in which the peak window/persistent currents are generated. Together, these findings imply that INaP and INaT arise from the same channels and that a simple modification of the Hodgkin-Huxley model can satisfactorily account for both currents. In the rostral ventral respiratory group (immediately caudal to preBötC), INaP was also detected, but peak conductance, current density, and input resistance were smaller than in preBötC region cells.
Key words: sodium channels; persistent current; respiration; pre-Bötzinger; pacemaker; riluzole; central pattern generator
Received Feb 11, 2004; revised April 14, 2005; accepted April 14, 2005.
This article has been cited by other articles:
C. A. Del Negro, K. Kam, J. A. Hayes, and J. L. Feldman
Asymmetric control of inspiratory and expiratory phases by excitability in the respiratory network of neonatal mice in vitro
J. Physiol., March 15, 2009; 587(6): 1217 - 1231.
[Abstract] [Full Text] [PDF]
J. E. Rubin, J. A. Hayes, J. L. Mendenhall, and C. A. Del Negro
Calcium-activated nonspecific cation current and synaptic depression promote network-dependent burst oscillations
PNAS, February 24, 2009; 106(8): 2939 - 2944.
[Abstract] [Full Text] [PDF]
Y. Dai, L. M. Jordan, and B. Fedirchuk
Modulation of Transient and Persistent Inward Currents by Activation of Protein Kinase C in Spinal Ventral Neurons of the Neonatal Rat
J Neurophysiol, January 1, 2009; 101(1): 112 - 128.
[Abstract] [Full Text] [PDF]
Z. M. Khaliq and B. P. Bean
Dynamic, Nonlinear Feedback Regulation of Slow Pacemaking by A-Type Potassium Current in Ventral Tegmental Area Neurons
J. Neurosci., October 22, 2008; 28(43): 10905 - 10917.
[Abstract] [Full Text] [PDF]
D. F. Donnelly
Spontaneous action potential generation due to persistent sodium channel currents in simulated carotid body afferent fibers
J Appl Physiol, May 1, 2008; 104(5): 1394 - 1401.
[Abstract] [Full Text] [PDF]
D. E. Featherstone and S. A. Shippy
Regulation of Synaptic Transmission by Ambient Extracellular Glutamate
Neuroscientist, April 1, 2008; 14(2): 171 - 181.
[Abstract] [PDF]
J. A. Hayes, J. L. Mendenhall, B. R. Brush, and C. A. Del Negro
4-Aminopyridine-sensitive outward currents in preBotzinger complex neurons influence respiratory rhythm generation in neonatal mice
J. Physiol., April 1, 2008; 586(7): 1921 - 1936.
[Abstract] [Full Text] [PDF]
H. Koizumi and J. C. Smith
Persistent Na+ and K+-Dominated Leak Currents Contribute to Respiratory Rhythm Generation in the Pre-Botzinger Complex In Vitro
J. Neurosci., February 13, 2008; 28(7): 1773 - 1785.
[Abstract] [Full Text] [PDF]
A. C. Jackson and B. P. Bean
State-Dependent Enhancement of Subthreshold A-Type Potassium Current by 4-Aminopyridine in Tuberomammillary Nucleus Neurons
J. Neurosci., October 3, 2007; 27(40): 10785 - 10796.
[Abstract] [Full Text] [PDF]
G. Zhong
Persistent sodium current in preBotzinger neurons is not necessary for respiratory rhythm generation in the neonatal mouse?
J. Physiol., June 1, 2007; 581(2): 429 - 429.
[Full Text] [PDF]
R. W. Pace, D. D. Mackay, J. L. Feldman, and C. A. Del Negro
Role of persistent sodium current in mouse preBotzinger Complex neurons and respiratory rhythm generation
J. Physiol., April 15, 2007; 580(2): 485 - 496.
[Abstract] [Full Text] [PDF]
R. D. Theiss, J. J. Kuo, and C. J. Heckman
Persistent inward currents in rat ventral horn neurones
J. Physiol., April 15, 2007; 580(2): 507 - 522.
[Abstract] [Full Text] [PDF]
L. K. Purvis, J. C. Smith, H. Koizumi, and R. J. Butera
Intrinsic Bursters Increase the Robustness of Rhythm Generation in an Excitatory Network
J Neurophysiol, February 1, 2007; 97(2): 1515 - 1526.
[Abstract] [Full Text] [PDF]
J. J. Kuo, R. H. Lee, L. Zhang, and C. J. Heckman
Essential role of the persistent sodium current in spike initiation during slowly rising inputs in mouse spinal neurones
J. Physiol., August 1, 2006; 574(3): 819 - 834.
[Abstract] [Full Text] [PDF]
|
|
|
|
 |
|