Abrogation of oxidative stress improves insulin sensitivity in the Ren-2 rat model of tissue angiotensin II overexpression

Mihaela C. Blendea, David Jacobs, Craig S Stump, Samy I. McFarlane, Cristina Ogrin, Gul Bahtyiar, Samir Stas, Pawan Kumar, Quan Sha, Carlos M. Ferrario, James R. Sowers

Research output: Contribution to journalArticle

119 Scopus citations

Abstract

To evaluate the role of renin-angiotensin system (RAS)-mediated oxidative stress in insulin resistance (IR), we compared the effects of the angiotensin II (ANG II) receptor blocker (ARB) valsartan and a superoxide dismutase (SOD) mimetic, tempol, on whole body glucose tolerance and soleus muscle insulin-stimulated glucose uptake in transgenic hypertensive TG(mREN-2)27 (Ren-2) rats. Ren-2 rats and Sprague-Dawley (SD) controls were given valsartan (30 mg/kg) or tempol (1 mmol/l) in their drinking water for 21 days. IR was measured by glucose tolerance testing (1 g/kg glucose ip). IR index (AUC glucose x AUCinsulin) was significantly higher in the Ren-2 animals compared with SD controls (30.5 ± 7.0 × 10 6 arbitrary units in Ren-2 vs. 10.2 ± 2.4 × 10 6 in SD, P < 0.01). Both valsartan and tempol treatment normalized Ren-2 IR index. Compared with SD controls (100%), there was a significant increase in superoxide anion production (measured by lucigenin-enhanced chemiluminescence) in soleus muscles of Ren-2 rats (133 ± 15%). However, superoxide production was reduced in both valsartan-and tempol-treated (85 ± 22% and 59 ± 12%', respectively) Ren-2 rats. Insulin (INS)-mediated 2-deoxyglucose (2-DG) uptake (%SD basal levels) was substantially lower in Ren-2 rat soleus muscle compared with SD (Ren-2 + INS = 110 ± 3% vs. SD + INS = 206 ± 12%, P < 0.05). However, Ren-2 rats treated with valsartan or tempol exhibited a significant increase in insulin-mediated 2-DG uptake compared with untreated transgenic animals. Improvements in skeletal muscle insulin-dependent glucose uptake and whole body IR in rats overexpressing ANG II by ARB or SOD mimetic indicate that oxidative stress plays an important role in ANG II-mediated insulin resistance.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume288
Issue number2 51-2
DOIs
Publication statusPublished - Feb 2005
Externally publishedYes

    Fingerprint

Keywords

  • Insulin resistance
  • Superoxide
  • Valsartan

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Biochemistry

Cite this