|
|
|
|
|
|
|
||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The Journal of General Physiology, Vol 82, 543-568, Copyright © 1983 by The Rockefeller University Press
ARTICLES |
C Vergara and R Latorre
The interaction of Ca2+ and Ba2+ with a Ca2+-activated K+ channel from rabbit skeletal muscle membranes is studied in planar lipid bilayers. At [Ca2+] greater than or equal to 100 microM in the cis side (the side to which the vesicles are added) and at positive voltages, the channel kinetics consisted of bursts of activity interrupted by long periods of quiescence. We found that the reciprocal of the mean burst time increases linearly with [Ca2+], whereas the mean time for the quiescent (closed) periods is independent of [Ca2+]. The number of quiescent periods is reduced by increasing [K+]. Micromolar amounts of cis Ba2+ do not activate the channel, but induce similar "slow" closings. Also, in this case, the mean burst time is inversely proportional to the [Ba2+] and the mean closed time is independent of [Ba2+]. Raising [K+] either symmetrically or only in the trans side relieved the Ba2+ effect. trans Ba2+ also induces changes in the slow kinetics, but in millimolar amounts. These results suggest that the quiescent periods correspond to a channel blocked by a Ba ion. The voltage dependence of the cis blockade indicates that the Ba2+ binding site is past the middle of the membrane field. The similarities in the slow kinetics induced by Ca2+ and Ba2+ suggest that Ca2+ blocks the channel by binding to the same site. However, binding of Ca2+ to the site is 10(5)- fold weaker.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  I. Carvacho, W. Gonzalez, Y. P. Torres, S. Brauchi, O. Alvarez, F. D. Gonzalez-Nilo, and R. Latorre Intrinsic Electrostatic Potential in the BK Channel Pore: Role in Determining Single Channel Conductance and Block J. Gen. Physiol., January 28, 2008; 131(2): 147 - 161. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Li, I. Berke, L. Chen, and Y. Jiang Gating and Inward Rectifying Properties of the MthK K+ Channel with and without the Gating Ring J. Gen. Physiol., January 29, 2007; 129(2): 109 - 120. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. N. Krishnan, J.-P. Bingham, S. H. Lee, P. Trombley, and E. Moczydlowski Functional Role and Affinity of Inorganic Cations in Stabilizing the Tetrameric Structure of the KcsA K+ Channel J. Gen. Physiol., August 29, 2005; 126(3): 271 - 283. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. I. Brelidze and K. L. Magleby Protons Block BK Channels by Competitive Inhibition with K+ and Contribute to the Limits of Unitary Currents at High Voltages J. Gen. Physiol., February 23, 2004; 123(3): 305 - 319. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. B. Park, H. J. Kim, P. D. Ryu, and E. Moczydlowski Effect of Phosphatidylserine on Unitary Conductance and Ba2+ Block of the BK Ca2+-activated K+ Channel: Re-examination of the Surface Charge Hypothesis J. Gen. Physiol., April 28, 2003; 121(5): 375 - 398. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Moshelion and N. Moran Potassium-Efflux Channels in Extensor and Flexor Cells of the Motor Organ of Samanea saman Are Not Identical. Effects of Cytosolic Calcium Plant Physiology, February 1, 2001; 125(2): 1142 - 1150. [Abstract] [Full Text]
|
|
|
|
|
|
M. Moshelion and N. Moran Potassium-Efflux Channels in Extensor and Flexor Cells of the Motor Organ of Samanea saman Are Not Identical. Effects of Cytosolic Calcium Plant Physiology, October 1, 2000; 124(2): 911 - 919. [Abstract] [Full Text]
|
|
|
|
 |
|
 J. I. Kourie Calcium dependence of C-type natriuretic peptide-formed fast K+ channel Am J Physiol Cell Physiol, July 1, 1999; 277(1): C43 - C50. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Leviel, D. Eladari, A. Blanchard, J.-S. Poumarat, M. Paillard, and R.-A. Podevin Pathways for HCO-3 exit across the basolateral membrane in rat thick limbs Am J Physiol Renal Physiol, June 1, 1999; 276(6): F847 - F856. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 O. F. Koster, G. P. Szigeti, and D. J. Beuckelmann Characterization of a [Ca2+]i-dependent current in human atrial and ventricular cardiomyocytes in the absence of Na+ and K+ Cardiovasc Res, January 1, 1999; 41(1): 175 - 187. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. C. Devor and R. A. Frizzell Modulation of K+ channels by arachidonic acid in T84 cells. II. Activation of a Ca2+-independent K+ channel Am J Physiol Cell Physiol, January 1, 1998; 274(1): C149 - C160. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. N. Khan, S. K. Smith, J. J. Morrison, and M. L. J. Ashford Ca2+ dependence and pharmacology of large-conductance K+ channels in nonlabor and labor human uterine myocytes Am J Physiol Cell Physiol, November 1, 1997; 273(5): C1721 - C1731. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. J. DiChiara and P. H. Reinhart Redox Modulation of hslo Ca2+-Activated K+ Channels J. Neurosci., July 1, 1997; 17(13): 4942 - 4955. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Solaro and C. Lingle Trypsin-sensitive, rapid inactivation of a calcium-activated potassium channel Science, September 18, 1992; 257(5077): 1694 - 1698. [Abstract] [PDF]
|
|
|
|
|
|
M. Gustin, B Martinac, Y Saimi, M. Culbertson, and C Kung Ion channels in yeast Science, September 12, 1986; 233(4769): 1195 - 1197. [Abstract] [PDF]
|
|
|
|
