Obesity and hypertension are risk factors for the development of chronic kidney disease. The mechanisms by which elevated blood pressure and fatty acids lead to the development of renal injury are incompletely understood. Here, we investigated the contributions of cholesterol and oxidative stress to renal endothelial dysfunction and glomerular injury in a model of obesity and hypertension. Male Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) were fed a normal diet, a high-fat diet, a high-fat diet with tempol, or a high-fat diet with simvastatin for up to 10 wk. Blood pressure was not altered by a high-fat diet or treatments. After 3 wk, renal afferent dilatory responses to acetylcholine were impaired in WKY rats and SHR fed a high-fat diet. Tempol treatment prevented this vascular dysfunction in both strains; however, simvastatin treatment demonstrated greater beneficial effects in the SHR. Albuminuria was observed in the SHR and was exacerbated by a high-fat diet. Tempol and simvastatin treatment significantly ameliorated albuminuria in the SHR fed a high-fat diet. Ten weeks on a high-fat resulted in an increase in urinary 8-isoprostane in WKY rats and SHR, and tempol and simvastatin treatment prevented this increase, indicating a reduction in renal oxidative stress. Monocyte chemoattractant protein-1 (MCP-1) excretion was significantly elevated by a high-fat diet in both strains, and tempol prevented this increase. Interestingly, simvastatin treatment had no effect on MCP-1 levels. These data indicate that tempol and simvastatin treatment via a reduction in oxidative stress improve renal endothelial function and decrease glomerular injury in a model of obesity and hypertension.
"A dose of 174 µmol/kg caused a decrease in MAP with more than 30 mmHg and when given in an effective dose (72–90 µmol/kg), Tempol reduced the blood pressure in all hypertensive models with evidence of oxidative stress . Moreover, Tempol administration ameliorated 8-isoprostane excretion in several hypertensive models , . Fractional excretions of sodium and potassium (FE Na and FE K) were calculated using standard formulae. "
[Show abstract][Hide abstract] ABSTRACT: While the presence of oxidative stress in chronic kidney disease (CKD) is well established, its relation to hypertensive renal hemodynamics remains unclear. We hypothesized that once CKD is established blood pressure and renal vascular resistance (RVR) no longer depend on reactive oxygen species. CKD was induced by bilateral ablation of 2/3 of each kidney. Compared to age-matched, sham-operated controls all ablated rats showed proteinuria, decreased glomerular filtration rate (GFR), more renal damage, higher mean arterial pressure (MAP), RVR and excretion of oxidative stress markers and hydrogen peroxide, while excretion of stable nitric oxide (NO) metabolites tended to decrease. We compared MAP, RVR, GFR and fractional excretion of sodium under baseline and during acute Tempol, PEG-catalase or vehicle infusion in rats with established CKD vs. controls. Tempol caused marked reduction in MAP in controls (96±5 vs.79±4 mmHg, P<0.05) but not in CKD (130±5 vs. 127±6 mmHg). PEG-catalase reduced MAP in both groups (controls: 102±2 vs. 94±4 mmHg, P<0.05; CKD: 118±4 vs. 110±4 mmHg, P<0.05), but did not normalize MAP in CKD rats. Tempol and PEG-catalase slightly decreased RVR in both groups. Fractional excretion of sodium was increased by both Tempol and PEG-catalase in both groups. PEG-catalase decreased TBARS excretion in both groups. In sum, although oxidative stress markers were increased, MAP and RVR did not depend more on oxidative stress in CKD than in controls. Therefore reactive oxygen species appear not to be important direct determinants of hypertensive renal hemodynamics in this model of established CKD.
PLoS ONE 02/2014; 9(2):e88596. DOI:10.1371/journal.pone.0088596 · 3.23 Impact Factor
"It is increased in adipose tissue during obesity and in diabetic kidneys, suggesting that inflammation of these tissues may be MCP- 1 dependent . Knight et al. also showed an increase in renal macrophage-specific CD68-positive staining in a model of obesity and hypertension . From these results, we can say that macrophages are the source of increased OS and renal injury in diabetes and obesity-induced renal injury. "
[Show abstract][Hide abstract] ABSTRACT: Oxidative stress has a critical role in the pathophysiology of several kidney diseases, and many complications of these diseases are mediated by oxidative stress, oxidative stress-related mediators, and inflammation. Several systemic diseases such as hypertension, diabetes mellitus, and hypercholesterolemia; infection; antibiotics, chemotherapeutics, and radiocontrast agents; and environmental toxins, occupational chemicals, radiation, smoking, as well as alcohol consumption induce oxidative stress in kidney. We searched the literature using PubMed, MEDLINE, and Google scholar with "oxidative stress, reactive oxygen species, oxygen free radicals, kidney, renal injury, nephropathy, nephrotoxicity, and induction". The literature search included only articles written in English language. Letters or case reports were excluded. Scientific relevance, for clinical studies target populations, and study design, for basic science studies full coverage of main topics, are eligibility criteria for articles used in this paper.
"Of note, this would imply that the prognostic impact of glomerular MAU (so not induced by statin use) in populations with a high prevalence of statin use, would be underestimated. The hypothesis that statin induced MAU is tubular in origin would also fit with the favorable effect of statins on cardiovascular disease and on progression of renal disease, as these effects are related to the reduction of glomerular MAU associated with the improvement of endothelial dysfunction , . "
[Show abstract][Hide abstract] ABSTRACT: Microalbuminuria (MAU) is considered as a predictor or marker of cardiovascular and renal events. Statins are widely prescribed to reduce cardiovascular risk and to slow down progression of kidney disease. But statins may also generate tubular MAU. The current observational study evaluated the impact of statin use on the interpretation of MAU as a predictor or marker of cardiovascular or renal disease.
We used cross-sectional data of ERICABEL, a cohort with 1,076 hypertensive patients. MAU was defined as albuminuria ≥20 mg/l. A propensity score was created to correct for "bias by indication" to receive a statin. As expected, subjects using statins vs. no statins had more cardiovascular risk factors, pointing to bias by indication. Statin users were more likely to have MAU (OR: 2.01, 95%CI: 1.34-3.01). The association between statin use and MAU remained significant after adjusting for the propensity to receive a statin based on cardiovascular risk factors (OR: 1.82, 95%CI: 1.14-2.91). Next to statin use, only diabetes (OR: 1.92, 95%CI: 1.00-3.66) and smoking (OR: 1.49, 95%CI: 0.99-2.26) were associated with MAU.
Use of statins is independently associated with MAU, even after adjusting for bias by indication to receive a statin. In the hypothesis that this MAU is of tubular origin, statin use can result in incorrect labeling of subjects as having a predictor or marker of cardiovascular or renal risk. In addition, statin use affected the association of established cardiovascular risk factors with MAU, blurring the interpretation of multivariable analyses.
PLoS ONE 02/2012; 7(2):e31639. DOI:10.1371/journal.pone.0031639 · 3.23 Impact Factor
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