HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mathie, A Articles by Cull-Candy, S G Search for Related Content PubMed PubMed Citation Articles by Mathie, A Articles by Cull-Candy, S G

MRC Receptor Mechanisms Research Group, Department of Pharmacology, University College London.

1. The inward rectification of the whole-cell current evoked by acetylcholine (ACh) and other nicotinic agonists in rat sympathetic ganglion neurones has been studied using patch-clamp recording techniques. The selective nicotinic agonist 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP) (20 microM) induced an average peak current of -367 pA at -50 mV but no detectable outward current at +50 mV. Similar observations were made with ACh and carbachol. 2. The current-voltage relation of the whole-cell response induced by DMPP was linear in the negative voltage range; however, there was no detectable outward current in the voltage range 0 to about +70 mV. Above +70 mV an outward current became clearly detectable. Rapid depolarizing jumps in the holding potential failed to reveal any rapidly decaying outward current. 3. The rectification was not alleviated by changing the main permeant cation, by removal of divalent cations from the intracellular or extracellular solutions or by altering the pH buffer in the extracellular solution from HEPES to Tris. 4. Intracellular magnesium ions can block the channel. This effect increases with depolarization, but dissociation outwards (i.e. permeation by Mg2+) appears to relieve the block at more extreme positive potentials. This effect alone, or in combination with the voltage dependence of the burst length, is unlikely to be able to account for the whole-cell rectification in intact cells, much less that seen in cells perfused with Mg2(+)-free intracellular medium. 5. When the reversal potential was shifted to approximately -50 mV (by the use of impermeant cations) nicotinic agonists produced small outward currents in the membrane potential range -20 to +10 mV while shifting it to about +40 mV produced small inward currents in the potential range 0 to +20 mV. The rectification therefore appears to be independent of the direction of current flow and is maximum at a potential positive to 0 mV. 6. At positive potentials the receptors desensitized much less than at negative potentials in the continued presence of agonist. Thus, exposure of the cells to a steady application of 30 microM-ACh produced no detectable response if the cell was at a positive potential, but when the cell was stepped to a negative potential in the continued presence of ACh (at a time when much of the ACh current would be expected to have desensitized), ACh induced a large inward current. The onset of the ACh current had a time constant of 10 ms. It then decayed with a time constant of 790 ms as desensitization developed.(ABSTRACT TRUNCATED AT 400 WORDS)

This article has been cited by other articles:

				O. Sacchi, M. L. Rossi, R. Canella, and R. Fesce Synaptic and Somatic Effects of Axotomy in the Intact, Innervated Rat Sympathetic Neuron J Neurophysiol, May 1, 2006; 95(5): 2832 - 2844. [Abstract] [Full Text] [PDF]

				I. L. Hanganu and H. J. Luhmann Functional Nicotinic Acetylcholine Receptors on Subplate Neurons in Neonatal Rat Somatosensory Cortex J Neurophysiol, July 1, 2004; 92(1): 189 - 198. [Abstract] [Full Text] [PDF]

				T. Rosenbaum, L. D. Islas, A. E. Carlson, and S. E. Gordon Dequalinium: A Novel, High-affinity Blocker of CNGA1 Channels J. Gen. Physiol., December 30, 2002; 121(1): 37 - 47. [Abstract] [Full Text] [PDF]

				X. Zhou, J. Ren, E. Brown, D. Schneider, Y. Caraballo-Lopez, and J. J. Galligan Pharmacological Properties of Nicotinic Acetylcholine Receptors Expressed by Guinea Pig Small Intestinal Myenteric Neurons J. Pharmacol. Exp. Ther., September 1, 2002; 302(3): 889 - 897. [Abstract] [Full Text] [PDF]

				F. Sgard, E. Charpantier, S. Bertrand, N. Walker, D. Caput, D. Graham, D. Bertrand, and F. Besnard A Novel Human Nicotinic Receptor Subunit, alpha 10, That Confers Functionality to the alpha 9-Subunit Mol. Pharmacol., January 1, 2002; 61(1): 150 - 159. [Abstract] [Full Text] [PDF]

				R. A. Giniatullin, E. M. Sokolova, S. Di Angelantonio, A. Skorinkin, M. V. Talantova, and A. Nistri Rapid Relief of Block by Mecamylamine of Neuronal Nicotinic Acetylcholine Receptors of Rat Chromaffin Cells In Vitro: An Electrophysiological and Modeling Study Mol. Pharmacol., October 1, 2000; 58(4): 778 - 787. [Abstract] [Full Text]

				A. P. Haghighi and E. Cooper A Molecular Link between Inward Rectification and Calcium Permeability of Neuronal Nicotinic Acetylcholine alpha 3beta 4 and alpha 4beta 2 Receptors J. Neurosci., January 15, 2000; 20(2): 529 - 541. [Abstract] [Full Text] [PDF]

				J. Zhang, Y. Xiao, G. Abdrakhmanova, W. Wang, L. Cleemann, K.J. Kellar, and M. Morad Activation and Ca2+ Permeation of Stably Transfected alpha 3/beta 4 Neuronal Nicotinic Acetylcholine Receptor Mol. Pharmacol., June 1, 1999; 55(6): 970 - 981. [Abstract] [Full Text]

				K. Sabey, K. Paradiso, J. Zhang, and J. H. Steinbach Ligand Binding and Activation of Rat Nicotinic alpha 4beta 2 Receptors Stably Expressed in HEK293 Cells Mol. Pharmacol., January 1, 1999; 55(1): 58 - 66. [Abstract] [Full Text]

				R. Furuya, K. Oka, I. Watanabe, Y. Kamiya, H. Itoh, and T. Andoh The Effects of Ketamine and Propofol on Neuronal Nicotinic Acetylcholine Receptors and P2X Purinoceptors in PC12 Cells Anesth. Analg., January 1, 1999; 88(1): 174 - 180. [Abstract] [Full Text] [PDF]

				A. P. Haghighi and E. Cooper Neuronal Nicotinic Acetylcholine Receptors Are Blocked by Intracellular Spermine in a Voltage-Dependent Manner J. Neurosci., June 1, 1998; 18(11): 4050 - 4062. [Abstract] [Full Text] [PDF]

				O. Sacchi, M. L. Rossi, R. Canella, and R. Fesce Synaptic Current at the Rat Ganglionic Synapse and Its Interactions With the Neuronal Voltage-Dependent Currents J Neurophysiol, February 1, 1998; 79(2): 727 - 742. [Abstract] [Full Text] [PDF]

				K. Poth, T. J. Nutter, J. Cuevas, M. J. Parker, D. J. Adams, and C. W. Luetje Heterogeneity of Nicotinic Receptor Class and Subunit mRNA Expression among Individual Parasympathetic Neurons from Rat Intracardiac Ganglia J. Neurosci., January 15, 1997; 17(2): 586 - 596. [Abstract] [Full Text] [PDF]

				B. Buisson, M. Gopalakrishnan, S. P. Arneric, J. P. Sullivan, and D. Bertrand Human alpha 4beta 2 Neuronal Nicotinic Acetylcholine Receptor in HEK 293 Cells: A Patch-Clamp Study J. Neurosci., December 15, 1996; 16(24): 7880 - 7891. [Abstract] [Full Text] [PDF]