The Journal of Neurophysiology Vol. 79 No. 1 January 1998, pp. 410-417
Copyright ©1998 The American Physiological Society

Facilitation of L-type Calcium Current in Thalamic Neurons

Paul J. Kammermeier¹ and Stephen W. Jones²

¹ Department of Neurosciences and ² Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106

Kammermeier, Paul J. and Stephen W. Jones. Facilitation of L-type calcium current in thalamic neurons. J. Neurophysiol. 79: 410-417, 1998. We have studied facilitation of the L-type calcium current in neurons acutely isolated from the ventrobasal nucleus of the rat thalamus. Currents were recorded after pretreatment with 1 µM -conotoxin GVIA and 5 µM -conotoxin MVIIC, to better isolate L-current. Long, strong depolarizations induced slow tail currents at negative voltages, but did not affect currents at voltages where channels were strongly activated. The initial peak tail current was not measurably increased. The time course of recovery from facilitation paralleled the time course of the tail current, indicating that facilitation does not outlast channel closing. The kinase inhibitors staurosporine and H-7 and the phosphatase inhibitor okadaic acid had no significant effect on L-current facilitation compared with control, but facilitation was greater with H-7 than with okadaic acid. The guanosine 5-triphosphate (GTP) analogs GTP--S and GDP--S did not affect facilitation. We conclude that L-current facilitation in thalamic neurons does not result from Ser/Thr phosphorylation, although phosphorylation may modulate facilitation. This form of facilitation differs kinetically and pharmacologically from facilitation induced by activation of G protein-coupled receptors.

This article has been cited by other articles:

				Y. Lu, Y. Lv, Y. Ye, Y. Wang, Y. Hong, M. E. Fortini, Y. Zhong, and Z. Xie A role for presenilin in post-stress regulation: effects of presenilin mutations on Ca2+ currents in Drosophila FASEB J, August 1, 2007; 21(10): 2368 - 2378. [Abstract] [Full Text] [PDF]

				N. Leresche, J. Hering, and R. C. Lambert Paradoxical Potentiation of Neuronal T-Type Ca2+ Current by ATP at Resting Membrane Potential J. Neurosci., June 16, 2004; 24(24): 5592 - 5602. [Abstract] [Full Text] [PDF]

				R. K. Powers and M. D. Binder Persistent Sodium and Calcium Currents in Rat Hypoglossal Motoneurons J Neurophysiol, January 1, 2003; 89(1): 615 - 624. [Abstract] [Full Text] [PDF]

				M. Aoyama, M. Murakami, T. Iwashita, Y. Ito, K. Yamaki, and S. Nakayama Slow Deactivation and U-Shaped Inactivation Properties in Cloned Cav1.2b Channels in Chinese Hamster Ovary Cells Biophys. J., January 1, 2003; 84(1): 709 - 724. [Abstract] [Full Text] [PDF]

				D. E. Kourennyi and S. Barnes Depolarization-Induced Calcium Channel Facilitation in Rod Photoreceptors Is Independent of G Proteins and Phosphorylation J Neurophysiol, July 1, 2000; 84(1): 133 - 138. [Abstract] [Full Text] [PDF]

				T. J. Kamp, H. Hu, and E. Marban Voltage-dependent facilitation of cardiac L-type Ca channels expressed in HEK-293 cells requires beta -subunit Am J Physiol Heart Circ Physiol, January 1, 2000; 278(1): H126 - H136. [Abstract] [Full Text] [PDF]