Type 1 diabetic model.
diabetic rats, diabetic, diabetes
DIABETES
For induction of diabetes, randomized rats were injected i.p. with 50 mg/kg STZ (S0130; Sigma-Aldrich) by adding the appropriate volume of the drug at 25 mg/mL in 10 mM sodium citrate (pH 4.5). Comparisons were made with vehicle-treated rats (10 mM sodium citrate [pH 4.5]). Glycemia, by tail-tip blood droplet analysis using a glucometer (Accu-Chek Aviva; Roche), was measured 3 weeks after STZ, and rats with glycemia ≥ 15 mmol/L were considered diabetic and included in the study.To confirm whether MR antagonism could preserve the GEnGlx and limit the development of DN, from 4 weeks after STZ administration, randomized diabetic rats were given daily s.c. injections of spironolactone (S3378; Sigma-Aldrich) at 50 mg/kg made up in corn oil (C8267; Sigma-Aldrich) for 28 days, and comparisons were made with vehicle-treated diabetic rats (corn oil). This spironolactone dose has previously been shown to have no effect on BP (To determine the importance of GEnGlx preservation in this model, enzymatic degradation of the GEnGlx with hyaluronidase was used. Briefly, randomized diabetic rats treated with spironolactone were given hyaluronidase (H3506; Sigma-Aldrich), 200 units in 1 mL, via tail vein injection 1 hour before being culled for tissue collection.Body weight was monitored regularly after STZ, and rats were placed on hydrophobic sand to collect urine. Urinary albumin was quantified with a rat albumin ELISA (E111-125, Bethyl Laboratories), and creatinine was measured using an enzymatic spectrophotometric assay (Konelab T-Series 981845; Thermo Fisher Scientific). uACR and urinary protein/creatinine ratio (uPCR) were calculated as previously described (