Single-channel recordings of apical membrane chloride conductance in A6 epithelial cells |
| |
Authors: | Deborah J. Nelson John M. Tang Lawrence G. Palmer |
| |
Affiliation: | (1) Department of Physiology, Rush Medical College, 60612 Chicago, Illinois;(2) Department of Physiology, Cornell University College of Medicine, 10021 New York, New York |
| |
Abstract: | Summary The apical membrane of epithelial cells from the A6 cell line grown on impermeable substrata was studied using the patch-clamp technique. We defined the apical membrane as that membrane in contact with the growth medium. In about 50% of the patches, channels with single-unit conductances of 360±45 pS in symmetrical 105mm NaCl solutions, and characteristic voltage-dependent inactivation were observed. Using excised membrane patches and varying the ionic composition of the bathing medium, we determined that the channels were anion selective, with a permeability ratio for Cl– over Na+ of about 91, calculated from the reversal potential using the constantfield equation. The channel was most active at membrane potentials between ±20 mV and inactivated, usually within a few seconds, at higher potentials of either polarity. Reactivation from this inactivation was slow, sometimes requiring minutes. In addition to its fully open state, the channel could also enter a flickering state, which appeared to involve rapid transitions to one or more submaximal conductance levels. The channel was inhibited by the disulfonic stilbene SITS in a manner characteristic of reversible open-channel blockers. |
| |
Keywords: | A6 cells chloride channels single-channel recording inactivation SITS |
本文献已被 SpringerLink 等数据库收录! |
|