Amiloride-sensitive and hco3--dependent short-circuit currents activated by
aldosterone and vasotocin in a6 cells.
Doi, Yasuo, and Yoshinori Marunaka.
Division of Respiratory Research, The Hospital for Sick Children Research
Institute and The University of Toronto Faculty of Medicine, Toronto,
Ontario, Canada, M5G 1X8
APStracts 2:0008C, 1995.
We studied the effects of aldosterone (ALDO) and arginine vasotocin (AVT) on
ion transport of renal epithelial cell line (A6) by measuring short-circuit
current (Isc). AVT induced a rapid, transient increase in Isc followed by a
decrease toward the baseline in cells untreated with ALDO. In cells treated
with ALDO, Isc showed a biphasic response to AVT, i.e., both transient and
sustained increases over 40 min after addition of AVT. The transient increase
was composed only of amiloride-insensitive Isc regardless of ALDO treatment,
while the sustained increase contained both amiloride-sensitive and
amiloride-insensitive components. The main part of the amiloride-insensitive,
sustained Isc depended on HCO3-. In cells treated with ALDO for 1 day,
removal of HCO3- in the bathing solution enhanced the amiloride-sensitive
component and decreased the amiloride-insensitive one. These data suggest
that 1) ALDO treatment is necessary for an AVT-induced sustained increase of
Isc, and 2) an HCO3--dependent Isc mainly contributes to the sustained
increase in amiloride-insensitive Isc.
Received 27 June 1994; accepted in final form 27 October 1994
APS Manuscript Number C0363-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1994 The American Physiological Society.
Published in APStracts on 27 February 1995.