Aldosterone regulation of sodium channel g-subunit mrna in cortical
collecting duct cells.
Denault, Deanna L., G[acute]eza Fejes-T[acute]oth, Anik[acute]o
N[acute]aray-Fejes-T[acute]oth.
Department of Physiology, Dartmouth Medical School, Lebanon, NH
03756
APStracts 3:0132C, 1996.
Specific regulatory mechanisms of aldosterone-stimulated Na+
reabsorption through the apical amiloride-sensitive channel are
unknown. In this study, we examined the effects of aldosterone on Na+
channel g-subunit mRNA levels in cultured rabbit cortical collecting
duct cells. Using reverse transcriptase PCR with RNA isolated from
aldosterone-treated cells and degenerate primers, a 446 bp PCR
product was amplified and further characterized by nested PCR and
sequencing. The nested PCR yielded a predicted 164 bp product.
Sequencing of the 446 bp PCR product revealed 83% nucleotide and 91%
amino acid identity to the rat colonic Na+ channel g-subunit. The
relative abundance of Na+ channel mRNA was determined by quantitative
PCR following a 24 hour aldosterone treatment. The results
demonstrate that Na+ channel g-subunit mRNA levels were significantly
higher (2.6 +/- 0.42) in aldosterone-treated cultures versus the
controls. This increase, however, is less than the aldosterone
-induced increase (3.2 +/- 2.0) in the amiloride-sensitive short
circuit current. These results indicate that Na+ channel g-subunit
mRNA levels are increased by aldosterone and that this increase is
likely to be responsible, at least in part, for the aldosterone
-induced Na+ current in the kidney.
Received 1 November 1995; accepted in final form 2 April 1996.
APS Manuscript Number C662-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 1 May 96