 |
 Previous Article | Next Article 
Journal of Neuroscience, Vol 13, 181-194, Copyright © 1993 by Society for Neuroscience
Multiple modes of N-type calcium channel activity distinguished by differences in gating kinetics
AH Delcour, D Lipscombe and RW Tsien
Department of Molecular and Cellular Physiology, Beckman Center, Stanford University Medical Center, California 94305.
In many neurons, N-type Ca2+ channels are a major Ca2+ entry pathway and
strongly influence neurotransmitter release. We carried out cell- attached
patch recordings (110 mM Ba2+ as charge carrier) to characterize the rapid
opening and closing kinetics of N-type Ca2+ channel gating in frog
sympathetic neurons. Single channels display at least three distinct
patterns of gating, characterized as low-, medium- , and high-rho o modes
on the basis of channel open probability (rho o) during depolarizing pulses
to -10 mV. Spontaneous transitions from one mode to another are infrequent,
with an exponential distribution of dwell times and mean sojourns of
approximately 10 sec in each mode. Thus, a channel typically undergoes
hundreds or thousands of open- closed transitions in one mode before
switching to a different mode. Transitions between modes during a
depolarization were occasionally detected, but were rare, as expected for
infrequent modal switching. Within each mode, the activation kinetics were
well described by a simple scheme (C2-C1-O), as previously reported for
other types of Ca2+ channels. Rate constants are strikingly different from
one mode to another, giving each mode its own characteristic kinetic
signature. The gating behavior at -10 mV ranges from brief openings
(approximately 0.3 msec) and long closures (10-20 msec) for low-rho o
gating to long openings (3 msec) and brief closures (approximately 1 msec)
for high- rho o gating. Intermediate values for mean open durations
(approximately 1.5 msec) and mean closed durations (approximately 3 msec)
were found for medium-rho o gating. In addition to being kinetically
distinct, channel openings in the low-rho o mode often exhibit a unitary
current approximately 0.2 pA larger than in the medium- or high-rho o mode.
Each mode is characterized by its own voltage dependence: activation occurs
at relatively negative potentials and is most steeply voltage dependent in
the high-rho o mode, while activation requires very strong depolarizations
and is weakly voltage dependent in the low-rho o mode. The proportion of
time spent in the individual modes varies greatly from one patch to
another, suggesting that modal gating may be subject to cellular control.
This article has been cited by other articles:
|
|
|
|
 
L. Ionescu, C. White, K.-H. Cheung, J. Shuai, I. Parker, J. E. Pearson, J. K. Foskett, and D.-O. D. Mak
Mode Switching Is the Major Mechanism of Ligand Regulation of InsP3 Receptor Calcium Release Channels
J. Gen. Physiol.,
November 26, 2007;
130(6):
631 - 645.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
S. Chakrapani, J. F Cordero-Morales, and E. Perozo
A Quantitative Description of KcsA Gating II: Single-Channel Currents
J. Gen. Physiol.,
October 29, 2007;
130(5):
479 - 496.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
C. P. Grabner and A. P. Fox
Stimulus-Dependent Alterations in Quantal Neurotransmitter Release
J Neurophysiol,
December 1, 2006;
96(6):
3082 - 3087.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
J. D. King Jr. and S. D. Meriney
Proportion of N-Type Calcium Current Activated by Action Potential Stimuli
J Neurophysiol,
December 1, 2005;
94(6):
3762 - 3770.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
S. Luvisetto, T. Fellin, M. Spagnolo, B. Hivert, P. F. Brust, M. M. Harpold, K. A. Stauderman, M. E. Williams, and D. Pietrobon
Modal Gating of Human CaV2.1 (P/Q-type) Calcium Channels: I. The Slow and the Fast Gating Modes and their Modulation by {beta} Subunits
J. Gen. Physiol.,
October 25, 2004;
124(5):
445 - 461.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
M. R. Bennett, L. Farnell, and W. G. Gibson
The Facilitated Probability of Quantal Secretion within an Array of Calcium Channels of an Active Zone at the Amphibian Neuromuscular Junction
Biophys. J.,
May 1, 2004;
86(5):
2674 - 2690.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
A. C. Dolphin
G Protein Modulation of Voltage-Gated Calcium Channels
Pharmacol. Rev.,
December 1, 2003;
55(4):
607 - 627.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
J. Magistretti, D. S. Ragsdale, and A. Alonso
Kinetic Diversity of Single-Channel Burst Openings Underlying Persistent Na+ Current in Entorhinal Cortex Neurons
Biophys. J.,
November 1, 2003;
85(5):
3019 - 3034.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
H. K. Lee and K. S. Elmslie
Reluctant Gating of Single N-Type Calcium Channels during Neurotransmitter-Induced Inhibition in Bullfrog Sympathetic Neurons
J. Neurosci.,
May 1, 2000;
20(9):
3115 - 3128.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
K. S. Elmslie
Identification of the Single Channels that Underlie the N-Type and L-Type Calcium Currents in Bullfrog Sympathetic Neurons
J. Neurosci.,
April 15, 1997;
17(8):
2658 - 2668.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
B G Frenguelli and R Malinow
Fluctuations in intracellular calcium responses to action potentials in single en passage presynaptic boutons of layer V neurons in neocortical slices.
Learn. Mem.,
January 1, 1996;
3(2-3):
150 - 159.
[Abstract]
[PDF]
|
|
|
|
