AJP - GI AJP: Renal Physiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Gastrointest Liver Physiol 276: G491-G498, 1999;
0193-1857/99 $5.00
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Grotjohann, I.
Right arrow Articles by Fromm, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Grotjohann, I.
Right arrow Articles by Fromm, M.
Vol. 276, Issue 2, G491-G498, February 1999

Electrogenic Na+ transport in rat late distal colon by natural and synthetic glucocorticosteroids

Ingo Grotjohann1, Jörg-Dieter Schulzke2, and Michael Fromm1

1 Institut für Klinische Physiologie and 2 Medizinische Klinik I Gastroenterologie und Infektiologie, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, D-12200 Berlin, Germany

The potency of in vitro-added corticosteroids to stimulate electrogenic Na+ absorption (JNa, the Na+ absorptive short-circuit current blockable by 10-4 M amiloride) was determined in rat late distal colon. JNa was determined 8 h after steroid addition from the drop in short-circuit current caused by 10-4 M amiloride. The concentration dependency of JNa was obtained for seven corticosteroids and compared with that established for aldosterone. Apparent mineralocorticoid potencies as determined from apparent Michaelis-Menten constant (Km) values were as follows: aldosterone 1.2 nM >> RU-28362 20 nM = deoxycorticosterone 20 nM > deoxycortisol 36 nM >=  dexamethasone 37 nM >> corticosterone 170 nM > cortisol 210 nM. These steroids exhibited Vmax values of 9-13 µmol · h-1 · cm-2 and similar concentration dependencies. Hill coefficients were between 1.6 and 2.1, suggesting cooperative effects between activated receptors. We conclude that corticosteroids exhibit graded mineralocorticoid potency instead of a sharp partition into exclusive groups of mineralocorticoid and nonmineralocorticoid hormones. The low apparent Km value of RU-28362 for mineralocorticoid action and the need for high concentrations of the mineralocorticoid antagonist mespirenone to block this response indicated that JNa in a native mammalian epithelium can be mediated by the glucocorticoid receptor. Glucocorticoid receptor-specific amounts of RU-28362 in combination with mineralocorticoid receptor-specific amounts of aldosterone or of the mineralocorticoid antagonist spironolactone showed cooperative action, suggesting a heterodimeric activation of JNa by the glucocorticoid receptor and mineralocorticoid receptor.

short-circuit current; corticosterone; RU-28362; spironolactone; heterodimerization


This article has been cited by other articles:


Home page
 J EndocrinolHome page
H J Novaira, D S Ornellas, T M Ortiga-Carvalho, X M Zhang, J Souza-Menezes, S E Guggino, W B Guggino, and M M Morales
Atrial natriuretic peptide modulates cystic fibrosis transmembrane conductance regulator chloride channel expression in rat proximal colon and human intestinal epithelial cells.
J. Endocrinol., April 1, 2006; 189(1): 155 - 165.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Gastrointest. Liver Physiol.Home page
K. M. Hoque, V. M. Rajendran, and H. J. Binder
Zinc inhibits cAMP-stimulated Cl secretion via basolateral K-channel blockade in rat ileum
Am J Physiol Gastrointest Liver Physiol, May 1, 2005; 288(5): G956 - G963.
[Abstract] [Full Text] [PDF]

Home page
 GutHome page
J C J Oprins, C van der Burg, H P Meijer, T Munnik, and J A Groot
Tumour necrosis factor {alpha} potentiates ion secretion induced by histamine in a human intestinal epithelial cell line and in mouse colon: involvement of the phospholipase D pathway
Gut, March 1, 2002; 50(3): 314 - 321.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Gastrointest. Liver Physiol.Home page
H. J. Epple, S. Amasheh, J. Mankertz, M. Goltz, J. D. Schulzke, and M. Fromm
Early aldosterone effect in distal colon by transcriptional regulation of ENaC subunits
Am J Physiol Gastrointest Liver Physiol, May 1, 2000; 278(5): G718 - G724.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online