Mechanism of anion permeation in the basolateral membrane of
isolated rabbit renal proximal tubule s3 segment.
Seki, George, Hideomi Yamada, Shigeo Taniguchi, Shu Uwatoko, Keiji
Suzuki, and Kiyoshi Kurokawa.
First Dept. of Internal Medicine, Tokyo University School of
Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan; and Health
Service Center, Tokyo University of Agriculture and Technology, 3-8-1
Harumicho, Fuchu city, Tokyo 183, Japan
APStracts 3:0336C, 1996.
Conventional and double-barrelled microelectrodes were used to examine
the anion selectivity of Cl- conductance in the basolateral membrane
of rabbit renal proximal tubule S3 segment. The permeability sequence
determined by anion replacements in the presence of K+ channel
blocker, quinine was SCN- > I- > Br- > Cl-
> gluconate- in both nonperfused and luminally-perfused
tubules. The anion-selective microelectrodes with higher sensitivity
to I- enabled us to measure intracellular I- activities. With these
electrodes we could compare the conductive movements of Cl- and I- in
response to the increase in bath K+ concentrations, and confirmed
that the conductance sequence was also I- > Cl-. While the
basolateral potential changes generated by Cl- and Br- currents were
stimulated by cAMP, the potential changes by SCN- and I- currents
were rather inhibited by cAMP. In addition, the conductive uptake of
I- was, in contrast with that of Cl-, inhibited by cAMP. These
results are consistent with the existence of at least two distinct
anion conductances in this membrane, which are differently regulated
by cAMP.
Received 8 July 1996; accepted in final form 9 October 1996.
APS Manuscript Number C377-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 November 1996