Journal of Neurophysiology, Vol 70, Issue 1 158-166, Copyright © 1993 by APS

ARTICLES

Transient Ca2+ currents in neurons isolated from rat lateral habenula

J. R. Huguenard, M. J. Gutnick and D. A. Prince
Department of Neurology and Neurological Sciences, Stanford University Medical Center, California 94305.

1. The properties of the low-voltage-activated transient Ca2+ current (LVA, IT) that underlies rhythmic burst firing in neurons of the lateral habenula (LHb) were examined to further our understanding of mechanisms that promote rhythmogenesis in the CNS. We compared these properties with those of IT in thalamic ventrobasal relay neurons (IVB) and of the more slowly inactivating ITs of thalamic reticular neurons (InRt). 2. Patch-clamp techniques were used to record whole cell Ca2+ currents in LHb cells acutely isolated from rats ranging in age from postnatal days 6 to 34 (P6-P34). The LVA current in LHb (ILHb) had a number of properties similar to those of IVB, including activation threshold (near -65 mV) and voltage-dependent steady-state activation [half-activation voltage (V1/2) = -58.5 mV, slope = 3.4 mV-1] and inactivation (V1/2 = -83.5 mV, slope = 5.0 mV-1) functions. 3. ILHb was characterized by biphasic inactivation, with a fast, voltage-dependent time constant (20-50 ms) similar to that of IVB and a slower, voltage-independent decay phase (time constant approximately 120 ms) that was much more prominent than in IVB. Recovery of ILHb from inactivation was monophasic (time constant, 507 ms at -90 mV), and was slower than for IVB and about the same as for InRt. 4. ILHb was relatively insensitive to equimolar substitution of Ba2+ for Ca2+, in contrast to IVB, which was decreased, and InRt, which was enhanced. 5. In computer simulations, these results could not be accounted for by a mixture of the two previously described IT types (IVB and InRt) in individual LHb cells.(ABSTRACT TRUNCATED AT 250 WORDS)

This article has been cited by other articles:

				J. Murbartian, J. M. Arias, and E. Perez-Reyes Functional Impact of Alternative Splicing of Human T-Type Cav3.3 Calcium Channels J Neurophysiol, December 1, 2004; 92(6): 3399 - 3407. [Abstract] [Full Text] [PDF]

				S.-y. Chang and U. Kim Ionic Mechanism of Long-Lasting Discharges of Action Potentials Triggered by Membrane Hyperpolarization in the Medial Lateral Habenula J. Neurosci., March 3, 2004; 24(9): 2172 - 2181. [Abstract] [Full Text] [PDF]

				E. Perez-Reyes Molecular Physiology of Low-Voltage-Activated T-type Calcium Channels Physiol Rev, January 1, 2003; 83(1): 117 - 161. [Abstract] [Full Text] [PDF]

				J. C. Gomora, J. Murbartian, J. M. Arias, J.-H. Lee, and E. Perez-Reyes Cloning and Expression of the Human T-Type Channel Cav3.3: Insights into Prepulse Facilitation Biophys. J., July 1, 2002; 83(1): 229 - 241. [Abstract] [Full Text] [PDF]

				S. M. Todorovic, E. Perez-Reyes, and C. J. Lingle Anticonvulsants But Not General Anesthetics Have Differential Blocking Effects on Different T-Type Current Variants Mol. Pharmacol., July 1, 2000; 58(1): 98 - 108. [Abstract] [Full Text]

				Z.-H. Pan Differential Expression of High- and Two Types of Low-Voltage-Activated Calcium Currents in Rod and Cone Bipolar Cells of the Rat Retina J Neurophysiol, January 1, 2000; 83(1): 513 - 527. [Abstract] [Full Text] [PDF]

				E. M. Talley, L. L. Cribbs, J.-H. Lee, A. Daud, E. Perez-Reyes, and D. A. Bayliss Differential Distribution of Three Members of a Gene Family Encoding Low Voltage-Activated (T-Type) Calcium Channels J. Neurosci., March 15, 1999; 19(6): 1895 - 1911. [Abstract] [Full Text] [PDF]

				J.-H. Lee, A. N. Daud, L. L. Cribbs, A. E. Lacerda, A. Pereverzev, U. Klockner, T. Schneider, and E. Perez-Reyes Cloning and Expression of a Novel Member of the Low Voltage-Activated T-Type Calcium Channel Family J. Neurosci., March 15, 1999; 19(6): 1912 - 1921. [Abstract] [Full Text] [PDF]

				T. S. McDowell, J. J. Pancrazio, P. Q. Barrett, and C. Lynch III Volatile Anesthetic Sensitivity of T-Type Calcium Currents in Various Cell Types Anesth. Analg., January 1, 1999; 88(1): 168 - 173. [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]

				Y.-W. Li, P. G. Guyenet, and D. A. Bayliss Voltage-Dependent Calcium Currents in Bulbospinal Neurons of Neonatal Rat Rostral Ventrolateral Medulla: Modulation by alpha 2-Adrenergic Receptors J Neurophysiol, February 1, 1998; 79(2): 583 - 594. [Abstract] [Full Text] [PDF]

				S. M. Todorovic and C. J. Lingle Pharmacological Properties of T-Type Ca2+ Current in Adult Rat Sensory Neurons: Effects of Anticonvulsant and Anesthetic Agents J Neurophysiol, January 1, 1998; 79(1): 240 - 252. [Abstract] [Full Text] [PDF]

				A. Tottene, A. Moretti, and D. Pietrobon Functional Diversity of P-Type and R-Type Calcium Channels in Rat Cerebellar Neurons J. Neurosci., October 15, 1996; 16(20): 6353 - 6363. [Abstract] [Full Text] [PDF]