|
|
|
|
|
|
|
||
Articles |
The endogenous Cl- conductance of Spodoptera frugiperda (Sf9) cells was studied 20-35 h after plating out of either uninfected cells or cells infected by a baculovirus vector carrying the cloned beta-galactosidase gene (beta-Gal cells). With the cation Tris+ in the pipette and Na+ in the bath, the reversal potential of whole-cell currents was governed by the prevailing Cl- equilibrium potential and could be fitted by the Goldman-Hodgkin-Katz equation with similar permeabilities for uninfected and beta-Gal cells. In the frequency range 0.12 < f < 300 Hz, the power density spectrum of whole-cell Cl- currents could be fitted by three Lorentzians. Independent of membrane potential, >50% of the total variance of whole-cell current fluctuations was accounted for by the low frequency Lorentzian (fc = 0.40 +/- 0.03 Hz, n = 6). Single-Cl- channels showed complex gating kinetics with long lasting (seconds) openings interrupted by similar long closures. In the open state, channels exhibited fast burst-like closures. Since the patches normally contained more than a single channel, it was not possible to measure open and closed dwell-time distributions for comparing single-Cl- channel activity with the kinetic features of whole-cell currents. However, the power density spectrum of Cl- currents of cell-attached and excised outside-out patches contained both high and low frequency Lorentzian components, with the corner frequency of the slow component (fc = 0.40 +/- 0.02 Hz, n = 4) similar to that of whole-cell current fluctuations. Chloride channels exhibited multiple conductance states with similar Goldman-Hodgkin-Katz-type rectification. Single-channel permeabilities covered the range from approximately 0.6.10(-14) cm5/s to approximately 6.10(-14) cm3/s, corresponding to a limiting conductance (gamma 150/150) of approximately 3.5 pS and approximately 35 pS, respectively. All states reversed near the same membrane potential, and they exhibited similar halide ion selectivity, P1 > PCl approximately PBr. Accordingly, Cl- current amplitudes larger than current flow through the smallest channel unit resolved seem to result from simultaneous open/shut events of two or more channel units.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Facebook 
Reddit 
Technorati 
Twitter What's this?
This article has been cited by other articles:
|
|
 |
|
  T. I. Rokitskaya, E. A. Kotova, and Y. N. Antonenko Tandem Gramicidin Channels Cross-linked by Streptavidin J. Gen. Physiol., April 28, 2003; 121(5): 463 - 476. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. L. Goforth, A. K. Chi, D. V. Greathouse, L. L. Providence, R. E. Koeppe II, and O. S. Andersen Hydrophobic Coupling of Lipid Bilayer Energetics to Channel Function J. Gen. Physiol., April 28, 2003; 121(5): 477 - 493. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Gonzalez-Perrett, K. Kim, C. Ibarra, A. E. Damiano, E. Zotta, M. Batelli, P. C. Harris, I. L. Reisin, M. A. Arnaout, and H. F. Cantiello Polycystin-2, the protein mutated in autosomal dominant polycystic kidney disease (ADPKD), is a Ca2+-permeable nonselective cation channel PNAS, December 22, 2000; (2000) 21456598. [Abstract] [Full Text]
|
|
|
|
 |
|
 O Peyronnet, V Vachon, J. Schwartz, and R Laprade Ion channel activity from the midgut brush-border membrane of gypsy moth (Lymantria dispar) larvae J. Exp. Biol., January 6, 2000; 203(12): 1835 - 1844. [Abstract] [PDF]
|
|
|
|
|
|
S. Gonzalez-Perrett, K. Kim, C. Ibarra, A. E. Damiano, E. Zotta, M. Batelli, P. C. Harris, I. L. Reisin, M. A. Arnaout, and H. F. Cantiello From the Cover: Polycystin-2, the protein mutated in autosomal dominant polycystic kidney disease (ADPKD), is a Ca2+-permeable nonselective cation channel PNAS, January 30, 2001; 98(3): 1182 - 1187. [Abstract] [Full Text] [PDF]
|
|
|
|
