Journal of Nutrition LabDiet, Your World of Nutritional Answers

Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
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
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Tsimaratos, M.
Right arrow Articles by Raccah, D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Tsimaratos, M.
Right arrow Articles by Raccah, D.
(Journal of Nutrition. 2001;131:3160-3165.)
© 2001 The American Society for Nutritional Sciences

Articles

{gamma}-Linolenic Acid Restores Renal Medullary Thick Ascending Limb Na+,K+-ATPase Activity in Diabetic Rats1 ,2

Michel Tsimaratos3, Thierry C. Coste, Anissa Djemli-Shipkolye, Philippe Vague, Gérard Pieroni* and Denis Raccah

UPRES EA 21–93, Faculté de Médecine Timone, 13385 Marseille cedex 05, France and * INSERM U 476, 13009 Marseille, France

3To whom correspondence should be addressed. E-mail: mtsima{at}mageos.com

In diabetes, the activity of {Delta}-6 desaturase, which converts linoleic acid (LA) into {gamma}-linolenic acid (GLA), the first step of arachidonic acid (AA) synthesis, is decreased, leading to alterations in membrane phospholipid composition. On the other hand, 12 wk after the onset of diabetes, Na+,K+-ATPase activity is reduced in many organs, including the kidney. The medullary thick ascending limb (MTAL) reduced Na+,K+-ATPase activity, whereas the sodium load secondary to glomerular hyperfiltration was increased. The aim of our study was to examine whether the changes in membrane fatty acid composition resulting from the inhibition of {Delta}-6 desaturase may be involved in the decreased Na+,K+-ATPase activity observed in the outer MTAL after 12 wk of diabetes. GLA is a fatty acid that by-passes the {Delta}-6 desaturase step. We measured the membrane fatty acid composition and the Na+,K+-ATPase activity in the renal outer medulla of control and streptozotocin (STZ)-induced diabetic rats 12 wk after the induction of diabetes. Measurements were performed after supplementation of control rats with sunflower oil (SO) or GLA for 12 wk, and supplementation of 12 wk diabetic rats with SO for 12 wk or with GLA for 6 or 12 wk. Supplementation with GLA not only prevented the decrease in Na+,K+-ATPase activity observed after 12 wk of diabetes but also time dependently stimulated Na+,K+-ATPase activity in the outer medulla. The changes in Na+,K+-ATPase activity were related to parallel changes in the amount of Na+,K+-ATPase {alpha}1 subunit protein. In addition, in diabetic rats only, Na+,K+-ATPase activity was positively correlated with the amount of AA present in cell membranes (r = 0.92, P < 0.05). Our results indicate that nutritional GLA supplementation increases Na+,K+-ATPase activity and expression in diabetic rats. In addition, the positive correlation between AA content and Na+,K+-ATPase activity suggests that in diabetic rats, alterations in membrane fatty acid composition contribute to the decreased Na+,K+-ATPase activity in outer medulla.

KEY WORDS: • arachidonic acid • {gamma}-linolenic acid • Na+,K+-ATPase • rats • medullary thick ascending limb






Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Copyright © 2001 by American Society for Nutrition