OBESITY INDUCED RENAL OXIDATIVE STRESS CONTRIBUTES TO RENAL INJURY IN SALT‐SENSITIVE HYPERTENSION

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Abstract
SUMMARY: In the present study, we determined the role of hypertension, oxidative stress and inflammation on kidney damage in a rodent model of obesity and diabetes. Hypertension was induced in male obese (db/db) mice and lean (db/m) mice by implantation of deoxycorticosterone acetate (DOCA) pellets and mice were allowed to drink water containing 1% salt. Mice were divided into six groups as follows: obese and lean control, obese and lean 1% salt (salt) and obese and lean DOCA plus 1% salt (DOCA‐salt). Blood pressure was significantly increased in lean and obese DOCA‐salt groups relative to their respective controls; however, there was no difference in blood pressure between the lean and obese control and salt groups. Urinary 8‐isoprostane was increased in obese control compared with lean control mice (1464 ± 267 vs 493 ± 53 pg/µmol creatinine, respectively) and this elevation was further increased in the obese DOCA‐salt treated mice (2430 ± 312 pg/µmol creatinine). Urinary monocyte chemoattractant protein‐1 excretion and CD68‐positive cells were also increased in both obese and lean DOCA‐salt groups compared with their respective controls. Furthermore, DOCA‐salt treatment increased collagen IV excretion in both obese and lean mice compared with controls, but there was no difference between obese and lean DOCA‐salt groups. Urinary albumin excretion was significantly increased in the obese compared with the lean DOCA‐salt mice (507 ± 160 vs 202 ± 48 µg/day, respectively). These data suggest that obese DOCA‐salt hypertensive mice exhibit greater renal injury than lean DOCA‐salt hypertensive mice in a manner independent of blood pressure and that this renal injury is associated with obesity related pre‐existing renal oxidative stress.