HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 286/4/R779    most recent 00396.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (9) Citing Articles via Google Scholar Google Scholar Articles by Okamoto, M. M. Articles by Machado, U. F. Search for Related Content PubMed PubMed Citation Articles by Okamoto, M. M. Articles by Machado, U. F.

THIRST AND VOLUME, ELECTROLYTE HOMEOSTASIS

Changes in dietary sodium consumption modulate GLUT4 gene expression and early steps of insulin signaling

¹Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo; ²Department of Nephrology, School of Medicine, University of Sao Paulo, Sao Paulo; and ³Experimental Medicine Department, Institute of Cardiology of the State of Rio Grande do Sul/University Foundation of Cardiology, Rio Grande do Sul, Brazil

Submitted 16 July 2003 ; accepted in final form 2 December 2003

Previous studies have shown that chronic salt overload increases insulin sensitivity, while chronic salt restriction decreases it. In the present study we investigated the influence of dietary sodium on 1) GLUT4 gene expression, by Northern and Western blotting analysis; 2) in vivo GLUT4 protein translocation, by measuring the GLUT4 protein in plasma membrane and microsome, before and after insulin injection; and 3) insulin signaling, by analyzing basal and insulin-stimulated tyrosine phosphorylation of insulin receptor (IR)-, insulin receptor substrate (IRS)-1, and IRS-2. Wistar rats were fed normal-sodium (NS-0.5%), low-sodium (LS-0.06%), or high-sodium diets (HS-3.12%) for 9 wk and were killed under pentobarbital anesthesia. Compared with NS rats, HS rats increased (P < 0.05) the GLUT4 protein in adipose tissue and skeletal muscle, whereas GLUT4 mRNA was increased only in adipose tissue. GLUT4 expression was unchanged in LS rats compared with NS rats. The GLUT4 translocation in HS rats was higher (P < 0.05) both in basal and insulin-stimulated conditions. On the other hand, LS rats did not increase the GLUT4 translocation after insulin stimulus. Compared with NS rats, LS rats showed reduced (P < 0.01) basal and insulin-stimulated tyrosine phosphorylation of IRS-1 in skeletal muscle and IRS-2 in liver, whereas HS rats showed enhanced basal tyrosine phosphorylation of IRS-1 in skeletal muscle (P < 0.05) and of IRS-2 in liver. In summary, increased insulin sensitivity in HS rats is related to increased GLUT4 gene expression, enhanced insulin signaling, and GLUT4 translocation, whereas decreased insulin sensitivity of LS rats does not involve changes in GLUT4 gene expression but is related to impaired insulin signaling.

low-sodium diet; high-sodium diet; insulin resistance; GLUT4 gene expression; insulin signaling

This article has been cited by other articles:

				G. F. Anhe, S. M. Hirabara, T. C. Turrer, L. C. Caperuto, F. F. Anhe, L. M. Ribeiro, A. C. Marcal, C. R. O. Carvalho, R. Curi, U. F. Machado, et al. Postpartum glycemic homeostasis in early lactating rats is accompanied by transient and specific increase of soleus insulin response through IRS2/AKT pathway Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2007; 292(6): R2225 - R2233. [Abstract] [Full Text] [PDF]