Angélica Müller

Role of Kinins in the Renoprotective Effect of Angiotensin–Converting Enzyme Inhibitors in Experimental Chronic Renal Failure

The aim of this study was to investigate whether the renoprotective effect of angiotensin–converting enzyme inhibitors (ACEIs) following 5/6 renal mass reduction is due in part to the potentiation of kinins. Three groups of rats with 5/6 renal mass reduction were studied during the 14 weeks following surgery. One group received no therapy (control); the second group was treated from the beginning with the ACEI ramipril (1 mg/kg/day) added to the drinking water, and the last group received ramipril plus a β2–bradykinin antagonist, HOE 140 (500 μg/kg/day) via osmotic minipumps. Plasma creatinine did not change in any group during the study. Urinary protein excretion rose in the controls from 9.18±1.6 to 45.0±5.6 mg/24 h at the end of the study. In ramipril group proteinuria was prevented (initial 7.5±1.0 and final 8.6±0.8 mg/24h). The effect of ramipril was abolished by HOE 140 (initial 11.6±2.0 and final 38.9±11 mg/ 24h). The systolic blood pressure of the controls increased from 106±2 to 144±5mmHg at the 14th week. Ramipril abolished the increase in systolic blood pressure. The effect of ramipril was reverted by HOE 140 (initial 108±2 and final 140±9 mmHg). Control rats had more severe histopathologic changes. Those animals receiving ramipril + HOE 140 displayed less severe glomerular changes, while rats treated only with ramipril had mild alterations. Thus the glomerular injury score was 2.11±0.32 for controls, 1.53±0.52 for rats treated with ramipril + HOE 140, and 0.06±0.04 for rats treated only with ramipril. The glomerular area was 20,886±1,410, 19,693±2,200 and 14,352±3,200 μm2, respectively, for the 3 groups. These results suggest that the protective effect of ACEIs in the development of chronic renal failure is partially mediated by kinins.

Lipid profile and plasma antioxidant status in sweet carbonated beverage-induced metabolic syndrome in rat

There is little information in the literature regarding the clinical significance of SVT on the prognosis of patients with severe PAH. A previous study by Tongers et al. analyzed SVT inpatientswith PHand [3] in contrast to our study, these authors included patients with chronic thromboembolic pulmonary hypertension, selecting a population not as homogeneous as the one in our study. It is noteworthy that the global incidence of atrial flutter and INRT was higher than described in left ventricular dysfunction, which could be related to morphological and functional changes that occur in both the atrium and the RV along with the modulation of autonomic activity. Moreover, there was a long interval between the diagnosis of PAH and the onset of SVT, with an average of five years which suggests that these arrhythmias would be a manifestation of long-standing PH and chronic heart failure [4]. Most episodes of SVT produced an important clinical deterioration. This could be related to the deleterious hemodynamic effects that the loss of atrial support produce on right ventricular filling in the presence of ventricular dysfunction. Thus, wemight consider that the initiation of these arrhythmias (AF or atrial flutter) could be a warning for the need for increasing specific therapy for PAH or to consider lung transplantation. Nevertheless, in short-term our patients with AF or atrial flutter showed a significant clinical improvement after restoration of SR, suggesting a role of TSV in the exacerbation of RV failure and that the maintenance of a stable SR could be an important goal in the treatment. According to our results EPS was a safe and effective procedure to diagnose the typeof SVTand to restore stable SR. Thehigh rate of success of radiofrequency ablation in the general population in common flutter (95%), and in INRT (100%), with recurrence rates of 5% per year is comparable to the rate of success obtained in our patients [5]. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [6].

Functional and Morphological Changes in Endocrine Pancreas following Cola Drink Consumption in Rats

Aim We report the effects of long-term cola beverage drinking on glucose homeostasis, endocrine pancreas function and morphology in rats. Methods Wistar rats drank: water (group W), regular cola beverage (group C, sucrose sweetened) or “light” cola beverage (group L, artificially sweetened). After 6 months, 50% of the animals in each group were euthanized and the remaining animals consumed water for the next 6 months when euthanasia was performed. Biochemical assays, insulinemia determination, estimation of insulin resistance (HOMA-IR), morphometry and immunohistochemistry evaluations were performed in pancreas. Results Hyperglycemia (16%, p<0.05), CoQ10 (coenzyme-Q10) decrease (−52%,p<0.01), strong hypertriglyceridemia (2.8-fold, p<0.01), hyperinsulinemia (2.4 fold, p<0.005) and HOMA-IR increase (2.7 fold, p<0.01) were observed in C. Group C showed a decrease in number of α cells (−42%, p<0.01) and β cells (−58%, p<0.001) and a moderate increase in α cells’ size after wash-out (+14%, p<0.001). Group L showed reduction in β cells’ size (−9%, p<0.001) and only after wash-out (L12) a 19% increase in size (p<0.0001) with 35% decrease in number of α cells (p<0.01). Groups C and L showed increase in α/β-cell ratio which was irreversible only in C (α/β = +38% in C6,+30% in C12, p<0.001vs.W6). Regular cola induced a striking increase in the cytoplasmic expression of Trx1 (Thioredoxin-1) (2.25-fold in C6 vs. W6; 2.7-fold in C12 vs. W12, p<0.0001) and Prx2 (Peroxiredoxin-2) (3-fold in C6 vs. W6; 2-fold in C12 vs. W12, p<0.0001). Light cola induced increase in Trx1 (3-fold) and Prx2 (2-fold) after wash-out (p<0.0001, L12 vs. W12). Conclusion Glucotoxicity may contribute to the loss of β cell function with depletion of insulin content. Oxidative stress, suggested by increased expression of thioredoxins and low circulating levels of CoQ10, may follow sustained hyperglycemia. A likely similar panorama may result from the effects of artificially sweetened cola though via other downstream routes.

Relative contribution of V-H+ATPase and NA+/H+ exchanger to bicarbonate reabsorption in proximal convoluted tubules of old rats

With aging, the kidney develops a progressive deterioration of several structures and functions. Proximal tubular acidification is impaired in old rats with a decrease in the activity of brush border Na+/H+ exchange and a fall of H‐ion flux measured with micropuncture experiments. In the present work we evaluate the contribution of 5‐N‐ethyl‐n‐isopropyl amiloride‐ (EIPA) and bafilomycin‐sensitive bicarbonate flux () in proximal convoluted tubules of young and aged rats. We performed micropuncture experiments inhibiting the Na+/H+ exchanger with EIPA (10−4 M) and the V‐H+ATPase with bafilomycin (10−6 M). We used antibodies against the NHE3 isoform of the Na+/H+ exchanger and the subunit E of the V‐H+ATPase for detecting by Western blot the abundance of these proteins in brush border membrane vesicles from proximal convoluted tubules of young and old rats. The abundance of NHE3 and the V‐H+ATPase was similar in 18‐month‐old and 3‐month‐old rats. The bicarbonate flux in old rats was 30% lower than in young rats. EIPA reduced by 60% and bafilomycin by 30% in young rats; in contrast, EIPA reduced by ∼40% and bafilomycin by ∼50% in old rats. The inhibited by bafilomycin was the same in young and old rats: 0.62 nmol · cm−2· s−1 and 0.71 nmol · cm−2· s−1, respectively. However, the EIPA‐sensitive fraction was larger in young than in old rats: 1.26 nmol · cm−2· s−1 vs. 0.85 nmol · cm−2· s−1, respectively. These results suggest that the component more affected in bicarbonate reabsorption of proximal convoluted tubules from aged rats is the Na+‐H+ exchanger, probably a NHE isoform different from NHE3.

Cardiorenal Involvement in Metabolic Syndrome Induced by Cola Drinking in Rats: Proinflammatory Cytokines and Impaired Antioxidative Protection.

We report experimental evidence confirming renal histopathology, proinflammatory mediators, and oxidative metabolism induced by cola drinking. Male Wistar rats drank ad libitum regular cola (C, n = 12) or tap water (W, n = 12). Measures. Body weight, nutritional data, plasma glucose, cholesterol fractions, TG, urea, creatinine, coenzyme Q10, SBP, and echocardiograms (0 mo and 6 mo). At 6 months euthanasia was performed. Kidneys were processed for histopathology and immunohistochemistry (semiquantitative). Compared with W, C rats showed (I) overweight (+8%, p < 0.05), hyperglycemia (+11%, p < 0.05), hypertriglyceridemia (2-fold, p < 0.001), higher AIP (2-fold, p < 0.01), and lower Q10 level (−55%, p < 0.05); (II) increased LV diastolic diameter (+9%, p < 0.05) and volume (systolic +24%, p < 0.05), posterior wall thinning (−8%, p < 0.05), and larger cardiac output (+24%, p < 0.05); (III) glomerulosclerosis (+21%, p < 0.05), histopathology (+13%, p < 0.05), higher tubular expression of IL-6 (7-fold, p < 0.001), and TNFα (4-fold, p < 0.001). (IV) Correlations were found for LV dimensions with IL-6 (74%, p < 0.001) and TNFα (52%, p < 0.001) and fully abolished after TG and Q10 control. Chronic cola drinking induced cardiac remodeling associated with increase in proinflammatory cytokines and renal damage. Hypertriglyceridemia and oxidative stress were key factors. Hypertriglyceridemic lipotoxicity in the context of defective antioxidant/anti-inflammatory protection due to low Q10 level might play a key role in cardiorenal disorder induced by chronic cola drinking in rats.

Rosuvastatin increases myocardial microvessels in SHR rats. Role of thioredoxin-1 and peroxiredoxin-2 expression

Fil: Cao, Gabriel Fernando. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Investigaciones Cardiologicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiologicas; Argentina

Effect of chronic inhibition of converting enzyme on proximal tubule acidification

The acute effect of angiotensin-converting enzyme inhibition (ACEi) on proximal convoluted tubule (PCT) function is well documented. However, the effect of chronic treatment is less known. The aim of this work was to evaluate the effect of chronic ACEi on PCT acidification (J(HCO(3)(-))). Rats received enalapril (10 mg.kg(-1).day(-1), added to the drinking water) during 3 mo. Micropuncture experiments were performed to measure the effect of chronic ACEi on J(HCO(3)(-)). Nitric oxide (NO.) synthesis in kidney cortex homogenates was assessed by quantifying the conversion of [(14)C]-L-arginine to [(14)C]-L-citrulline. Western blot analysis was performed to determine the abundances of V-H(+)ATPase and NHE3 isoform of the Na(+)/H(+) exchanger in proximal brush-border membrane vesicles (BBMV). Enalapril treatment induced an approximately 50% increase in J(HCO(3)(-)). Luminal perfusion with ethyl-isopropyl amiloride (EIPA) 10(-4)M or bafilomycin 10(-6)M decreased J(HCO(3)(-)) by approximately 60% and approximately 30%, respectively, in both control and enalapril-treated rats. The effect of EIPA and bafilomycin on absolute J(HCO(3)(-)) was larger in enalapril-treated than in control rats. Acute inhibition of NO. synthesis with N(G)-nitro-L-arginine methyl ester abolished the enalapril-induced increase in J(HCO(3)(-)). Cortex homogenates from enalapril-treated rats displayed a 46% increase in nitric oxide synthase (NOS) activity compared with those from untreated animals. Enalapril treatment did not affect the abundances of NHE3 and V-H(+)ATPase in BBMV. Our results suggest that PCT acidification is increased during chronic ACEi probably due to an increase in NO. synthesis, which would stimulate Na(+)/H(+) exchange and electrogenic proton transport.

Beneficial Effect of Moderate Exercise in Kidney of Rat after Chronic Consumption of Cola Drinks

Aim The purpose of this study was to investigate the effect of moderate intensity exercise on kidney in an animal model of high consumption of cola soft drinks. Methods Forty-eight Wistar Kyoto rats (age: 16 weeks; weight: 350–400 g) were assigned to the following groups: WR (water runners) drank water and submitted to aerobic exercise; CR (cola runners) drank cola and submitted to aerobic exercise; WS (water sedentary) and CS (cola sedentary), not exercised groups. The aerobic exercise was performed for 5 days per week throughout the study (24 weeks) and the exercise intensity was gradually increased during the first 8 weeks until it reached 20 meters / minute for 30 minutes. Body weight, lipid profile, glycemia, plasma creatinine levels, atherogenic index of plasma (AIP) and systolic blood pressure (SBP) were determined. After 6 months all rats were sacrificed. A kidney histopathological score was obtained using a semiquantitative scale. Glomerular size and glomerulosclerosis were estimated by point-counting. The oxidative stress and pro-inflammatory status were explored by immunohistochemistry. A one way analysis of variance (ANOVA) with Tukey-Kramer post-hoc test or the Kruskal-Wallis test with Dunn’s post-hoc test was used for statistics. A value of p < 0.05 was considered significant. Results At 6 months, an increased consumption of cola soft drink was shown in CS and CR compared with water consumers (p<0.0001). Chronic cola consumption was associated with increased plasma triglycerides, AIP, heart rate, histopathological score, glomerulosclerosis, oxidative stress and pro-inflammatory status. On the other hand, moderate exercise prevented these findings. No difference was observed in the body weight, SBP, glycemia, cholesterol and plasma creatinine levels across experimental groups. Conclusions This study warns about the consequences of chronic consumption of cola drinks on lipid metabolism, especially regarding renal health. Additionally, these findings emphasize the protective role of exercise training on renal damage.

Exercise Ameliorates Endocrine Pancreas Damage Induced by Chronic Cola Drinking in Rats.

Purpose This study evaluates whether the daily practice of an exercise routine might protect from endocrine pancreas damage in cola drinking rats. Methods Forty-eight Wistar rats were randomly assigned to 4 groups depending on a) beverage consumption ad libitum, water (W) or cola beverage (C), and b) physical activity, sedentary (S) or treadmill running (R). Accordingly, 4 groups were studied: WS (water sedentary), WR (water runner), CS (cola sedentary) and CR (cola runner). Body weight, nutritional data, plasma levels of glucose, creatinine, total cholesterol and cholesterol fractions, and triglycerides (enzymocolorimetry), and systolic blood pressure (plethysmography) were measured. After 6 months, euthanasia was performed (overdose sodium thiopental). Pancreatic tissue was immediately excised and conventionally processed for morphometrical and immunohistochemical determinations. Results The effects of running and chronic cola drinking on pancreas morphology showed interaction (p<0.001) rather than simple summation. Cola drinking (CS vs WS) reduced median pancreatic islet area (-30%, 1.8 104 μm2 vs 2.58 104 μm2, p<0.0001) and median β-cell mass (-43%, 3.81 mg vs 6.73 mg, p<0.0001), and increased median α/β ratio (+49%, 0.64 vs 0.43, p< 0.001). In water drinking rats (WR vs WS), running reduced median α-cell mass (-48%, 1.48 mg vs 2.82 mg, p<0.001) and α/β ratio (-56%, 0.19 vs 0.43, p<0.0001). Differently, in cola drinking rats (CR vs CS), running partially restored median islet area (+15%, 2.06 104 μm2 vs 1.79 104 μm2, p<0.05), increased median β-cell mass (+47%, 5.59 mg vs 3.81 mg, p <0.0001) and reduced median α/β ratio (-6%, 0.60 vs 0.64, p<0.05). Conclusion This study is likely the first reporting experimental evidence of the beneficial effect of exercise on pancreatic morphology in cola-drinking rats. Presently, the increase of nearly 50% in β cells mass by running in cola drinking rats is by far the most relevant finding. Moderate running, advisably indicated in cola consumers and patients at risk of diabetes, finds here experimental support.

Carvedilol protects the peritubular capillaries and kidney structure in spontaneously hypertensive rats

Fil: Cao, Gabriel Fernando. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Investigaciones Cardiologicas (i); Argentina