The Journal of Neurophysiology Vol. 78 No. 3 September 1997, pp. 1334-1340
Copyright ©1997 The American Physiological Society

Calcium Channel Subtypes in Lamprey Sensory and Motor Neurons

A. El Manira and N. Bussières

Department of Neuroscience, Nobel Institute for Neurophysiology, Karolinska Institutet, S-171 77 Stockholm, Sweden

El Manira, A. and N. Bussières. Calcium channel subtypes in lamprey sensory and motor neurons. J. Neurophysiol. 78: 1334-1340, 1997. Pharmacologically distinct calcium channels have been characterized in dissociated cutaneous sensory neurons and motoneurons of the larval lamprey spinal cord. To enable cell identification, sensory dorsal cells and motoneurons were selectively labeled with fluorescein-coupled dextran amine in the intact spinal cord in vitro before dissociation. Calcium channels present in sensory dorsal cells, motoneurons, and other spinal cord neurons were characterized with the use of whole cell voltage-clamp recordings and specific calcium channel agonist and antagonists. The results show that a transient low-voltage-activated (LVA) calcium current was present in a proportion of sensory dorsal cells but not in motoneurons, whereas high-voltage-activated (HVA) calcium currents were seen in all neurons recorded. The different components of HVA current were dissected pharmacologically and similar results were obtained for both dorsal cells and motoneurons. The N-type calcium channel antagonist -conotoxin-GVIA(-CgTx) blocked >70% of the HVA current. A large part of the -CgTx block was reversed after washout of the toxin. The L-type calcium channel antagonist nimodipine blocked ~15% of the total HVA current. The dihydropyridine agonist (±)-BayK 8644 markedly increased the amplitude of the calcium channel current. The BayK-potentiated current was not affected by -CgTx, indicating that the reversibility of the -CgTx effect is not due to a blockade of L-type channels. Simultaneous application of -CgTx and nimodipine left ~15% of the HVA calcium channel current, a small part of which was blocked by the P/Q-type channel antagonist -agatoxin-IVA. In the presence of the three antagonists, the persistent residual current (~10%) was completely blocked by cadmium. Our results provide evidence for the existence of HVA calcium channels of the N, L, and P/Q types and other HVA calcium channels in lamprey sensory neurons and motoneurons. In addition, certain types of neurons express LVA calcium channels.

This article has been cited by other articles:

				E. Nanou, A. Kyriakatos, P. Kettunen, and A. El Manira Separate signalling mechanisms underlie mGluR1 modulation of leak channels and NMDA receptors in the network underlying locomotion J. Physiol., June 15, 2009; 587(12): 3001 - 3008. [Abstract] [Full Text] [PDF]

				E. Nanou, A. Kyriakatos, A. Bhattacharjee, L. K. Kaczmarek, G. Paratcha, and A. El Manira Na+-mediated coupling between AMPA receptors and KNa channels shapes synaptic transmission PNAS, December 30, 2008; 105(52): 20941 - 20946. [Abstract] [Full Text] [PDF]

				A. D. McClellan, M. O. Kovalenko, J. A. Benes, and D. J. Schulz Spinal Cord Injury Induces Changes in Electrophysiological Properties and Ion Channel Expression of Reticulospinal Neurons in Larval Lamprey J. Neurosci., January 16, 2008; 28(3): 650 - 659. [Abstract] [Full Text] [PDF]

				D. Hess, E. Nanou, and A. El Manira Characterization of Na+-Activated K+ Currents in Larval Lamprey Spinal Cord Neurons J Neurophysiol, May 1, 2007; 97(5): 3484 - 3493. [Abstract] [Full Text] [PDF]

				M. Huss, A. Lansner, P. Wallen, A. El Manira, S. Grillner, and J. H. Kotaleski Roles of Ionic Currents in Lamprey CPG Neurons: A Modeling Study J Neurophysiol, April 1, 2007; 97(4): 2696 - 2711. [Abstract] [Full Text] [PDF]

				D. E. Schmitt, R. H. Hill, and S. Grillner The Spinal GABAergic System Is a Strong Modulator of Burst Frequency in the Lamprey Locomotor Network J Neurophysiol, October 1, 2004; 92(4): 2357 - 2367. [Abstract] [Full Text] [PDF]

				Z. Liu, J. Ren, and T. H Murphy Decoding of synaptic voltage waveforms by specific classes of recombinant high-threshold Ca2+ channels J. Physiol., December 1, 2003; 553(2): 473 - 488. [Abstract] [Full Text] [PDF]

				P. Kettunen, D. Hess, and A. E. Manira mGluR1, But Not mGluR5, Mediates Depolarization of Spinal Cord Neurons by Blocking a Leak Current J Neurophysiol, October 1, 2003; 90(4): 2341 - 2348. [Abstract] [Full Text] [PDF]

				R. R. Buss, C. W. Bourque, and P. Drapeau Membrane Properties Related to the Firing Behavior of Zebrafish Motoneurons J Neurophysiol, February 1, 2003; 89(2): 657 - 664. [Abstract] [Full Text] [PDF]

				L. Cangiano, P. Wallen, and S. Grillner Role of Apamin-Sensitive KCa Channels for Reticulospinal Synaptic Transmission to Motoneuron and for the Afterhyperpolarization J Neurophysiol, July 1, 2002; 88(1): 289 - 299. [Abstract] [Full Text] [PDF]

				G.-Y. Hu, Z. Biro, R. H. Hill, and S. Grillner Intracellular QX-314 Causes Depression of Membrane Potential Oscillations in Lamprey Spinal Neurons During Fictive Locomotion J Neurophysiol, June 1, 2002; 87(6): 2676 - 2683. [Abstract] [Full Text] [PDF]

				P. Kettunen, P. Krieger, D. Hess, and A. El Manira Signaling Mechanisms of Metabotropic Glutamate Receptor 5 Subtype and Its Endogenous Role in a Locomotor Network J. Neurosci., March 1, 2002; 22(5): 1868 - 1873. [Abstract] [Full Text] [PDF]

				S. Grillner, P. Wallen, R. Hill, L. Cangiano, and A. E. Manira Ion channels of importance for the locomotor pattern generation in the lamprey brainstem-spinal cord J. Physiol., May 15, 2001; 533(1): 23 - 30. [Abstract] [Full Text] [PDF]

				D. Hess and A. El Manira Characterization of a high-voltage-activated IA current with a role in spike timing and locomotor pattern generation PNAS, April 12, 2001; (2001) 91096198. [Abstract] [Full Text]

				A. Buschges, M. A. Wikstrom, S. Grillner, and A. El Manira Roles of High-Voltage-Activated Calcium Channel Subtypes in a Vertebrate Spinal Locomotor Network J Neurophysiol, December 1, 2000; 84(6): 2758 - 2766. [Abstract] [Full Text] [PDF]

				A. El Manira and P. Wallen Mechanisms of Modulation of a Neural Network Physiology, August 1, 2000; 15(4): 186 - 191. [Abstract] [Full Text] [PDF]

				P. Krieger, J. Hellgren-Kotaleski, P. Kettunen, and A. J. El Manira Interaction between Metabotropic and Ionotropic Glutamate Receptors Regulates Neuronal Network Activity J. Neurosci., July 15, 2000; 20(14): 5382 - 5391. [Abstract] [Full Text] [PDF]

				P. Krieger, A. Buschges, and A. el Manira Calcium Channels Involved in Synaptic Transmission From Reticulospinal Axons in Lamprey J Neurophysiol, April 1, 1999; 81(4): 1699 - 1705. [Abstract] [Full Text] [PDF]

				J. Tegner and S. Grillner Interactive Effects of the GABABergic Modulation of Calcium Channels and Calcium-Dependent Potassium Channels in Lamprey J Neurophysiol, March 1, 1999; 81(3): 1318 - 1329. [Abstract] [Full Text] [PDF]

				F. P. Elsen and J.-M. Ramirez Calcium Currents of Rhythmic Neurons Recorded in the Isolated Respiratory Network of Neonatal Mice J. Neurosci., December 15, 1998; 18(24): 10652 - 10662. [Abstract] [Full Text] [PDF]

				D. Hess and A. El Manira Characterization of a high-voltage-activated IA current with a role in spike timing and locomotor pattern generation PNAS, April 24, 2001; 98(9): 5276 - 5281. [Abstract] [Full Text] [PDF]