| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Department of Psychiatry, Mt Sinai School of Medicine, Bronx, NY.
1. The effects of carbachol on hippocampal pyramidal neurones were studied in tissue slices in vitro with intracellular microelectrodes, employing current clamp and voltage clamp methods. 2. The calcium-dependent potassium current, IAHP, and the voltage-dependent potassium current, IM, were both reversibly blocked by the application of carbachol (5-10 microM). 3. Carbachol (1-10 microM) induced a steady inward current under circumstances in which both IAHP and IM were inactive. This inward current was sometimes difficult to reverse upon carbachol wash-out, an effect possibly related to receptor desensitization. 4. The depolarizing effect of carbachol was reversed by 0.1 microM-atropine, and exhibited an apparent dissociation coefficient of 1.2 microM for carbachol and 18 nM for pirenzepine, indicating that it is mediated by activation of an M1 muscarinic receptor. 5. The depolarizing effect or inward current induced by carbachol was completely blocked by the potassium channel blockers caesium, tetraethylammonium and barium. 6. The slope of the current-voltage (I-V) plots in carbachol was reduced in the majority of cells, and crossed the control I-V plots at a negative membrane potential. The reversal potentials in carbachol shifted in a positive direction when bathing potassium concentration was increased. 7. In a number of cells, the I-V curves in carbachol were parallel to or converged positively with the control I-V curves. 8. The effects of carbachol were compared to those of serotonin, which increases a 'pure' potassium conductance. Serotonin (10 microM) produced an increase in the slope of the I-V curve, with a reversal potential sensitive to changes in bathing potassium concentration. The carbachol reversal potential values were negative to those of serotonin at 5 and 10 mM-potassium. The equilibrium potentials for carbachol and serotonin were equal at 25 mM-potassium. 9. The negative values of the reversal potential at 5 and 10 mM-potassium and the occurrence of non-crossing I-V characteristics in carbachol could be explained by postulating a second effect of carbachol: namely, a non-specific conductance increase in the dendrites. 10. It is concluded that carbachol depolarizes pyramidal cells in the hippocampus by blocking a voltage-insensitive potassium leak channel and does so by activating M1 muscarinic receptors. In addition, carbachol may also activate a second conductance in the dendrites, which could account for the anomalous I-V characteristics sometimes seen in response to carbachol in these cells.
This article has been cited by other articles:
|
|
 |
|
  D. B. Carr and D. J. Surmeier M1 Muscarinic Receptor Modulation of Kir2 Channels Enhances Temporal Summation of Excitatory Synaptic Potentials in Prefrontal Cortex Pyramidal Neurons J Neurophysiol, May 1, 2007; 97(5): 3432 - 3438. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. G. J. Allen and D. A. Brown Modulation of the excitability of cholinergic basal forebrain neurones by KATP channels J. Physiol., January 15, 2004; 554(2): 353 - 370. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. L. Colgin, E. A. Kramar, C. M. Gall, and G. Lynch Septal Modulation of Excitatory Transmission in Hippocampus J Neurophysiol, October 1, 2003; 90(4): 2358 - 2366. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Takayasu, M. Iino, N. Furuya, and S. Ozawa Muscarine-Induced Increase in Frequency of Spontaneous EPSCs in Purkinje Cells in the Vestibulo-Cerebellum of the Rat J. Neurosci., July 16, 2003; 23(15): 6200 - 6208. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. H. Shalinsky, J. Magistretti, L. Ma, and A. A. Alonso Muscarinic Activation of a Cation Current and Associated Current Noise in Entorhinal-Cortex Layer-II Neurons J Neurophysiol, September 1, 2002; 88(3): 1197 - 1211. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Fujino and D. Oertel Cholinergic Modulation of Stellate Cells in the Mammalian Ventral Cochlear Nucleus J. Neurosci., September 15, 2001; 21(18): 7372 - 7383. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. B. Belousov, B. F. O'Hara, and J. V. Denisova Acetylcholine Becomes the Major Excitatory Neurotransmitter in the Hypothalamus In Vitro in the Absence of Glutamate Excitation J. Neurosci., March 15, 2001; 21(6): 2015 - 2027. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Saar, Y. Grossman, and E. Barkai Long-Lasting Cholinergic Modulation Underlies Rule Learning in Rats J. Neurosci., February 15, 2001; 21(4): 1385 - 1392. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. MAY, M. M. BEAUDET, R. L. PARSONS, and K. M. BRAAS PACAP Modulates Rat Sympathetic Neuron Depolarization Through IP3 Ann. N.Y. Acad. Sci., December 1, 2000; 921(1): 186 - 194. [Full Text] [PDF]
|
|
|
|
|
|
K. Shimono, F. Brucher, R. Granger, G. Lynch, and M. Taketani Origins and Distribution of Cholinergically Induced beta Rhythms in Hippocampal Slices J. Neurosci., November 15, 2000; 20(22): 8462 - 8473. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Roberto and M. Brunelli PACAP-38 Enhances Excitatory Synaptic Transmission in the Rat Hippocampal CA1 Region Learn. Mem., September 1, 2000; 7(5): 303 - 311. [Abstract] [Full Text]
|
|
|
|
|
|
X. M. Shao and J. L. Feldman Acetylcholine Modulates Respiratory Pattern: Effects Mediated by M3-Like Receptors in PreBotzinger Complex Inspiratory Neurons J Neurophysiol, March 1, 2000; 83(3): 1243 - 1252. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. R. McQuiston and D. V. Madison Muscarinic Receptor Activity Has Multiple Effects on the Resting Membrane Potentials of CA1 Hippocampal Interneurons J. Neurosci., July 15, 1999; 19(14): 5693 - 5702. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Kolaj and L. P. Renaud Vasopressin-Induced Currents in Rat Neonatal Spinal Lateral Horn Neurons Are G-Protein Mediated and Involve Two Conductances J Neurophysiol, October 1, 1998; 80(4): 1900 - 1910. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. E. Schnee and B. S. Brown Selectivity of Linopirdine (DuP 996), a Neurotransmitter Release Enhancer, in Blocking Voltage-Dependent and Calcium-Activated Potassium Currents in Hippocampal Neurons J. Pharmacol. Exp. Ther., August 1, 1998; 286(2): 709 - 717. [Abstract] [Full Text]
|
|
|
|
|
|
T. Aosaki, K. Kiuchi, and Y. Kawaguchi Dopamine D1-Like Receptor Activation Excites Rat Striatal Large Aspiny Neurons In Vitro J. Neurosci., July 15, 1998; 18(14): 5180 - 5190. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Stuart and N. Spruston Determinants of Voltage Attenuation in Neocortical Pyramidal Neuron Dendrites J. Neurosci., May 15, 1998; 18(10): 3501 - 3510. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Schweitzer, S. G. Madamba, and G. R. Siggins Somatostatin Increases a Voltage-Insensitive K+ Conductance in Rat CA1 Hippocampal Neurons J Neurophysiol, March 1, 1998; 79(3): 1230 - 1238. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Kolaj, S. J. Shefchyk, and L. P. Renaud Two Conductances Mediate Thyrotropin-Releasing-Hormone-Induced Depolarization of Neonatal Rat Spinal Preganglionic and Lateral Horn Neurons J Neurophysiol, September 1, 1997; 78(3): 1726 - 1729. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Tsubokawa and W. N. Ross Muscarinic Modulation of Spike Backpropagation in the Apical Dendrites of Hippocampal CA1 Pyramidal Neurons J. Neurosci., August 1, 1997; 17(15): 5782 - 5791. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Klink and A. Alonso Ionic Mechanisms of Muscarinic Depolarization in Entorhinal Cortex Layer II Neurons J Neurophysiol, April 1, 1997; 77(4): 1829 - 1843. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. D. Fraser and B. A. MacVicar Cholinergic-Dependent Plateau Potential in Hippocampal CA1 Pyramidal Neurons J. Neurosci., July 1, 1996; 16(13): 4113 - 4128. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Haj-Dahmane and R. Andrade Muscarinic Activation of a Voltage-Dependent Cation Nonselective Current in Rat Association Cortex J. Neurosci., June 15, 1996; 16(12): 3848 - 3861. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
