| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Morphophysiology, Instituto de Biologia Molecular e Celular (IBMC), Porto, Portugal
2 Anatomy, Histology and Embryology, Medical and Health Science Centre, University of Debrecen, Debrecen, Hungary
* To whom correspondence should be addressed. E-mail: safronov{at}ibmc.up.pt.
Ionic conductances underlying excitability in tonically firing neurons (TFNs) from substantia gelatinosa (SG) were studied by the patch-clamp method in rat spinal cord slices. Ca2+-dependent K+ (KCA) conductance sensitive to apamin was found to prolong the interspike intervals and stabilize firing evoked by a sustained membrane depolarization. Suppression of Ca2+ and KCA currents, however, did not abolish the basic pattern of tonic firing indicating that it was generated by voltage-gated Na+ and K+ currents. Na+ and K+ channels were further analyzed in somatic nucleated patches. Na+ channels exhibited fast activation and inactivation kinetics, and followed two-exponential time course of recovery from inactivation. The major K+ current was carried through tetraethylammonium (TEA)-sensitive rapidly activating delayed-rectifier (KDR) channels with a slow inactivation. The TEA-insensitive transient A-type K+ (KA) current was very small in patches and was strongly inactivated at resting potential. Block of KDR rather than KA conductance by 1 mM TEA lowered the frequency and stability of firing. Intracellular staining with biocytin revealed at least three morphological groups of TFNs. Finally, on the basis of present data we created a model of TFN and showed that Na+ and KDR currents are sufficient to generate a basic pattern of tonic firing. It is concluded that the balanced contribution of all ionic conductances described here is important for generation and modulation of tonic firing in SG neurons.
This article has been cited by other articles:
|
|
 |
|
  V. Pinto, P. Szucs, V. A. Derkach, and B. V. Safronov Monosynaptic convergence of C- and A{delta}-afferent fibres from different segmental dorsal roots on to single substantia gelatinosa neurones in the rat spinal cord J. Physiol., September 1, 2008; 586(17): 4165 - 4177. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. J. Dougherty and S. Hochman Spinal Cord Injury Causes Plasticity in a Subpopulation of Lamina I GABAergic Interneurons J Neurophysiol, July 1, 2008; 100(1): 212 - 223. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. A. Graham, A. M. Brichta, and R. J. Callister Recording Temperature Affects the Excitability of Mouse Superficial Dorsal Horn Neurons, In Vitro J Neurophysiol, May 1, 2008; 99(5): 2048 - 2059. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. Pinto, V. A. Derkach, and B. V. Safronov Role of TTX-Sensitive and TTX-Resistant Sodium Channels in A{delta}- and C-Fiber Conduction and Synaptic Transmission J Neurophysiol, February 1, 2008; 99(2): 617 - 628. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. A. Graham, A. M. Brichta, P. R. Schofield, and R. J. Callister Altered potassium channel function in the superficial dorsal horn of the spastic mouse J. Physiol., October 1, 2007; 584(1): 121 - 136. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. A. Graham, A. M. Brichta, and R. J. Callister Moving From an Averaged to Specific View of Spinal Cord Pain Processing Circuits J Neurophysiol, September 1, 2007; 98(3): 1057 - 1063. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. M. Sonner and J. E. Stern Functional role of A-type potassium currents in rat presympathetic PVN neurones J. Physiol., August 1, 2007; 582(3): 1219 - 1238. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. F. A. Santos, S. Rebelo, V. A. Derkach, and B. V. Safronov Excitatory interneurons dominate sensory processing in the spinal substantia gelatinosa of rat J. Physiol., May 15, 2007; 581(1): 241 - 254. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Wolff, P. Heugel, G. Hempelmann, A. Scholz, J. Muhling, and A. Olschewski Clonidine reduces the excitability of spinal dorsal horn neurones Br. J. Anaesth., March 1, 2007; 98(3): 353 - 361. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Balasubramanyan, P. L. Stemkowski, M. J. Stebbing, and P. A. Smith Sciatic Chronic Constriction Injury Produces Cell-Type-Specific Changes in the Electrophysiological Properties of Rat Substantia Gelatinosa Neurons J Neurophysiol, August 1, 2006; 96(2): 579 - 590. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. U. R. Asghar, P. F. Cilia La Corte, F. E. N. LeBeau, M. A. Dawoud, S. C. Reilly, E. H. Buhl, M. A. Whittington, and A. E. King Oscillatory activity within rat substantia gelatinosa in vitro: a role for chemical and electrical neurotransmission J. Physiol., January 1, 2005; 562(1): 183 - 198. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. A Graham, A. M Brichta, and R. J Callister In vivo responses of mouse superficial dorsal horn neurones to both current injection and peripheral cutaneous stimulation J. Physiol., December 15, 2004; 561(3): 749 - 763. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. V. Melnick, S. F. A. Santos, and B. V. Safronov Mechanism of spike frequency adaptation in substantia gelatinosa neurones of rat J. Physiol., September 1, 2004; 559(2): 383 - 395. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
