Martina Schaan de Souza

Renal denervation in an animal model of diabetes and hypertension: Impact on the autonomic nervous system and nephropathy

BackgroundThe effects of renal denervation on cardiovascular reflexes and markers of nephropathy in diabetic-hypertensive rats have not yet been explored.MethodsAim: To evaluate the effects of renal denervation on nephropathy development mechanisms (blood pressure, cardiovascular autonomic changes, renal GLUT2) in diabetic-hypertensive rats. Forty-one male spontaneously hypertensive rats (SHR) ~250 g were injected with STZ or not; 30 days later, surgical renal denervation (RD) or sham procedure was performed; 15 days later, glycemia and albuminuria (ELISA) were evaluated. Catheters were implanted into the femoral artery to evaluate arterial pressure (AP) and heart rate variability (spectral analysis) one day later in conscious animals. Animals were killed, kidneys removed, and cortical renal GLUT2 quantified (Western blotting).ResultsHigher glycemia (p < 0.05) and lower mean AP were observed in diabetics vs. nondiabetics (p < 0.05). Heart rate was higher in renal-denervated hypertensive and lower in diabetic-hypertensive rats (384.8 ± 37, 431.3 ± 36, 316.2 ± 5, 363.8 ± 12 bpm in SHR, RD-SHR, STZ-SHR and RD-STZ-SHR, respectively). Heart rate variability was higher in renal-denervated diabetic-hypertensive rats (55.75 ± 25.21, 73.40 ± 53.30, 148.4 ± 93 in RD-SHR, STZ-SHR- and RD-STZ-SHR, respectively, p < 0.05), as well as the LF component of AP variability (1.62 ± 0.9, 2.12 ± 0.9, 7.38 ± 6.5 in RD-SHR, STZ-SHR and RD-STZ-SHR, respectively, p < 0.05). GLUT2 renal content was higher in all groups vs. SHR.ConclusionsRenal denervation in diabetic-hypertensive rats improved previously reduced heart rate variability. The GLUT2 equally overexpressed by diabetes and renal denervation may represent a maximal derangement effect of each condition.

Reduced cortical renal GLUT1 expression induced by angiotensin-converting enzyme inhibition in diabetic spontaneously hypertensive rats

Diabetes in spontaneously hypertensive rats is associated with cortical renal GLUT1 and GLUT2 overexpression. Our objective was to evaluate the effect of the angiotensin-converting enzyme blockade on cortical renal GLUT1 and GLUT2 expression, urinary albumin and urinary TGF-beta1. Streptozotocin, 50 mg/kg, or citrate buffer (N = 16) was administered as a single injection into the tail vein in adult spontaneously hypertensive rats (approximately 260 g). Thirty days later, these diabetic spontaneously hypertensive rats received ramipril by gavage: 0.01 mg x kg(-1) x day(-1) (D0.01, N = 14), 1 mg x kg(-1) x day(-1) (D1, N = 9) or water (D, N = 11) for 15 days. Albumin and TGF-beta1 (24-h urine), direct arterial pressure, renal tissue angiotensin-converting enzyme activity (fluorometric assay), and GLUT1 and GLUT2 protein levels (Western blot, renal cortex) were determined. Glycemia and glycosuria were higher (P < 0.05) in the diabetic rats compared with controls, but similar between the diabetic groups. Diabetes in spontaneously hypertensive rats lowered renal tissue angiotensin-converting enzyme activity (40%), which was reduced further when higher ramipril doses were used. Diabetes associated with hypertension raised GLUT1 by 28% (P < 0.0001) and GLUT2 by 76% (P = 0.01), and both doses of ramipril equally reduced cortical GLUT1 (D vs D1 and vs D0.01, P < or = 0.001). GLUT2 levels were reduced in D0.01 (P < 0.05 vs D). Diabetes increased urinary albumin and TGF-beta1 urinary excretion, but the 15-day ramipril treatment (with either dose) did not reduce them. In conclusion, ramipril is effective in lowering renal tissue angiotensin-converting enzyme activity, as well as blocking cortical GLUT1 overexpression, which may be beneficial in arresting the development of diabetic nephropathy.

Renal GLUT1 reduction depends on angiotensin-converting enzyme inhibition in diabetic hypertensive rats.

AIMS Angiotensin-converting enzyme (ACE) inhibitors are used in diabetic kidney disease to reduce systemic/intra-glomerular pressure. The objective of this study was to investigate whether reducing blood pressure (BP) could modulate renal glucose transporter expression, and urinary markers of diabetic nephropathy in diabetic hypertensive rats treated with ramipril or amlodipine. MAIN METHODS Diabetes was induced in spontaneously-hypertensive rats (~210 g) by streptozotocin (50mg/kg). Thirty days later, animals received ramipril 15 μg/kg/day (R, n=10), or amlodipine 10mg/kg/day (A, n=8,) or water (C, n=10) by gavage. After 30-day treatment, body weight, glycaemia, urinary albumin and TGF-β1 (enzyme-linked immunosorbent assay) and BP (tail-cuff pressure method) were evaluated. Kidneys were removed for evaluation of renal cortex glucose transporters (Western blotting) and renal tissue ACE activity (fluorometric assay). KEY FINDINGS After treatments, body weight (p=0.77) and glycaemia (p=0.22) were similar among the groups. Systolic BP was similarly reduced (p<0.001) in A and R vs. C (172.4 ± 3.2; 1867 ± 3.7 and 202.2 ± 4.3 mmHg; respectively). ACE activity (C: 0.903 ± 0.086; A: 0.654 ± 0.025, and R: 0.389 ± 0.057 mU/mg), albuminuria (C: 264.8 ± 15.4; A: 140.8 ± 13.5 and R: 102.8 ± 6.7 mg/24h), and renal cortex GLUT1 content (C: 46.81 ± 4.54; A: 40.30 ± 5.39 and R: 26.89 ± 0.79 AU) decreased only in R (p<0.001, p<0.05 and p<0.001; respectively). SIGNIFICANCE We concluded that the blockade of the renin-angiotensin system with ramipril reduced early markers of diabetic nephropathy, a phenomenon that cannot be specifically related to decreased BP levels.

Comparison between adherence assessments and blood glucose monitoring measures to predict A1c in type 1 diabetes

Materials and methods Four instruments evaluated adherence: Self-Care Inventory-Revised version (SCI-R), a self-administered survey; Diabetes Self Monitoring Profile (DSMP), a survey administered by trained researchers; a categorical (yes/no/ sometimes) self-report question (“In the past month, did you take care of your diabetes as your doctor recommended?”); and a continuous adherence self-evaluation, which ranged from 0-100. BGM frequency was evaluated by self-report, BGM diary, and meter download. Glycemic control was assessed by A1c (HPLC).

Prevalence of diabetes mellitus in Brazil: a systematic review with meta-analysis

Materials and methods Cross-sectional and cohort studies published between 1980 and 2014 were independently identified by two reviewers, without language restriction, in five databases (PubMed, Cochrane Library, EMBASE, LILACS and SciELO). Random effects models were used to estimate the prevalence of DM for the general population, as well as the trends for the last decades. Heterogeneity was assessed by I statistics.