pH and external Ca2+ regulation of a small conductance Cl- channel in kidney distal tubule

Citation
R. Sauve et al., pH and external Ca2+ regulation of a small conductance Cl- channel in kidney distal tubule, BBA-BIOMEMB, 1509(1-2), 2000, pp. 73-85
Citations number
35
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES
ISSN journal
00052736 → ACNP
Volume
1509
Issue
1-2
Year of publication
2000
Pages
73 - 85
Database
ISI
SICI code
0005-2736(200012)1509:1-2<73:PAECRO>2.0.ZU;2-K
Abstract
A single channel characterization of the Cl- channels in distal nephron was undertaken using Vesicles prepared from plasma membranes of isolated rabbi t distal tubules. The presence in this vesicle preparation of ClC-K type Cl - channels was first established by immunodetection using an antibody raise d against ClC-K isoforms. A ClC-Kl based functional characterization was ne xt performed by investigating the pH and external Ca2+ regulation of a smal l conductance Cl- channel which we identified previously by channel incorpo ration experiments. Acidification of the cis (external) solution from pH 7. 4 to 6.5 led to a dose-dependent inhibition of the channel open probability Po Similarly, changing the trans pH from 7.4 to 6.8 resulted in a 4-fold d ecrease of the channel Po with no effect on the channel conductance. Channe l activity also appeared to be regulated by cis (external) Ca2+ concentrati on, with a dose-dependent increase in channel activity as a function of the cis Ca2+ concentration. It is concluded on the basis of these results that the small conductance Cl- channel present in rabbit distal tubules is func tionally equivalent to the ClC-Kl channel in the rat. In addition, the pres ent work constitutes the first single channel evidence for a chloride chann el regulated by external Ca2+. (C) 2000 Elsevier Science B.V. All rights re served.