The Triad Na+ Activated Na+ Channel (Nax)-Salt Inducible KINASE (SIK) and (Na+ + K+)-ATPase: Targeting the Villains to Treat Salt Resistant and Sensitive Hypertension

The Na⁺-activated Na⁺ channel (Nax) and salt-inducible kinase (SIK) are stimulated by increases in local Na⁺ concentration, affecting (Na⁺ + K⁺)-ATPase activity. To test the hypothesis that the triad Nax/SIK/(Na⁺ + K⁺)-ATPase contributes to kidney injury and salt-sensitive hypertension (HTN), uninephrectomized male Wistar rats (200 g; n = 20) were randomly divided into 4 groups based on a salt diet (normal salt diet; NSD-0.5% NaCl-or high-salt diet; HSD-4% NaCl) and subcutaneous administration of saline (0.9% NaCl) or deoxycorticosterone acetate (DOCA, 8 mg/kg), as follows: Control (CTRL), CTRL-Salt, DOCA, and DOCA-Salt, respectively. After 28 days, the following were measured: kidney function, blood pressure, (Na⁺ + K⁺)-ATPase and SIK1 kidney activities, and Nax and SIK1 renal expression levels. SIK isoforms in kidneys of CTRL rats were present in the glomerulus and tubular epithelia; they were not altered by HSD and/or HTN. CTRL-Salt rats remained normotensive but presented slight kidney function decay. HSD rats displayed augmentation of the Nax/SIK/(Na⁺ + K⁺)-ATPase pathway. HTN, kidney injury, and kidney function decay were present in all DOCA rats; these were aggravated by HSD. DOCA rats presented unaltered (Na⁺ + K⁺)-ATPase activity, diminished total SIK activity, and augmented SIK1 and Nax content in the kidney cortex. DOCA-Salt rats expressed SIK1 activity and downregulation in (Na⁺ + K⁺)-ATPase activity in the kidney cortex despite augmented Nax content. The data of this study indicate that the (Na⁺ + K⁺)-ATPase activity response to SIK is attenuated in rats under HSD, independent of HTN, as a mechanism contributing to kidney injury and salt-sensitive HTN.

Association between blood pressure and angiotensin-converting enzymes activity in prepubertal children ∗

OBJECTIVES

Angiotensin-converting enzymes' (ACEs) relationship with blood pressure (BP) during childhood has not been clearly established. We aimed to compare ACE and ACE2 activities between BMI groups in a sample of prepubertal children, and to characterize the association between these enzymes' activities and BP.

METHODS

Cross-sectional study of 313 children aged 8-9 years old, included in the birth cohort Generation XXI (Portugal). Anthropometric measurements and 24-h ambulatory BP monitoring were performed. ACE and ACE2 activities were quantified by fluorometric methods.

RESULTS

Overweight/obese children demonstrated significantly higher ACE and ACE2 activities, when compared to their normal weight counterparts [median (P25-P75), ACE: 39.48 (30.52-48.97) vs. 42.90 (35.62-47.18) vs. 43.38 (33.49-49.89) mU/ml, P for trend = 0.009; ACE2: 10.41 (7.58-15.47) vs. 21.56 (13.34-29.09) vs. 29.00 (22.91-34.32) pM/min per ml, P for trend < 0.001, in normal weight, overweight and obese children, respectively]. In girls, night-time systolic BP (SBP) and diastolic BP (DBP) increased across tertiles of ACE activity ( P < 0.001 and P  = 0.002, respectively). ACE2 activity was associated with higher night-time SBP and DBP in overweight/obese girls ( P  = 0.037 and P  = 0.048, respectively) and night-time DBP in the BMI z-score girl adjusted model ( P  = 0.018). Median ACE2 levels were significantly higher among nondipper girls (16.7 vs. 11.6 pM/min per ml, P  = 0.009).

CONCLUSIONS

Our work shows that obesity is associated with activation of the renin-angiotensin-aldosterone system, with significant increase of ACE and ACE2 activities already in childhood. Also, we report sex differences in the association of ACE and ACE2 activities with BP.

Abstract 085: Pediatric Dyslipidemia Is Associated With Higher Urinary Angiotensin Converting Enzyme Activity And Blood Pressure Values In A Brazilian Cohort

Angiotensin converting enzyme (ACE) upregulation in adults contributes to cardiometabolic diseases including dyslipidemia and atherosclerosis.

Objective: Investigate whether ACE activity is modulated in pediatric dyslipidemia.

Methods: We evaluated anthropometric measurements, blood pressure and fasting lipid concentrations of 360 individuals (190 boys and 170 girls) aged from 6 to 19 year (mean 11.6). Categorization was done according to the levels of each lipoprotein (Total cholesterol (TC), triglycerides (TG), LDL-C, HDL-C, and non-HDL) into three groups: normolipidemic, borderline and dyslipidemic; reference values were according to American Academy of Pediatrics and Brazilian Pediatric Society. ACE activity in urine was measured with the substrates Z-FHL-OH and hippuryl-HL-OH. ACE activity ratio to infer N-domain activity was calculated (Z-FHL/h-HL).

Results: Dyslipidemic levels of HDL-C, TG and LDL-C were observed in 23%, 9% and 3% of the participants, respectively. These clinical alterations were more frequent in obese children (Chi-square, p <0.001). ACE activity (Z-FHL) was higher in the groups with borderline and dyslipidemic values of HDL-C than in normolipidemic group (0.077 vs 0.070 vs 0.037 nmol/min/mg of creatinine, p = 0.01). The ratio of ACE activity was augmented in HDL-C borderline group when compared to HDL-C normolipidemic group (5.06 vs 2.39, p <0.01) and in LDL-C dyslipidemic group than in LDL-C borderline and LDL-C normolipidemic groups (8.66 vs 1.84 vs 2.88, p = 0.02). Volunteers with normal levels of TG presented lower diastolic blood pressure (DBP) mmHg (p = 0.02), percentile of DBP (p < 0.01), and percentile of systolic blood pressure (SBP) (p <0.01) than volunteers with borderline and dyslipidemic levels of TG. Also, increased DBP mmHg was observed in borderline and dyslipidemic HDL-C groups when compared to normolipidic HDL-C group.

Conclusion: Pediatric hypertriglyceridemia, HDL-C deficiency and high LDL-C were related to higher urinary ACE activity (mainly N-domain). ACE modulation can contribute to higher risk of hypertension and other cardiometabolic alterations still in childhood and adolescence. Also, impairment in lipoprotein levels was associated with higher blood pressure values.

Abstract P256: Higher Angiotensin Converting Enzymes Activities Are Observed In Covid-19 Positive Volunteers

The high transmissibility and the broad spectrum of clinical manifestations of COVID-19 are in part due to the high affinity of SARS-CoV-2 for its receptor, Angiotensin Converting Enzyme 2 (ACE2). The depletion of the biological functions of ACE2, due to the internalization of the receptor along with SARS-CoV-2, leads to impairment of Renin Angiotensin System (RAS), which can contribute to COVID-19 pathogenesis. In addition, genetic differences in RAS may be associated with more severe symptoms and complications observed in COVID-19 patients. This study aims to perform a comparative analysis between COVID-19 positive patients and uninfected individuals, to correlate such disease profiles with ACE I/D (Insertion/Deletion) and ACE2 G8790A polymorphisms, and their enzymatic activities. The anthropometric, demographic, clinical and cardiovascular parameters of 764 individuals from Ipaussu/SP (Brazil) were evaluated. ACE and ACE2 activities were measured by fluorometric assays, and assessment of both enzymes polymorphisms was performed by PCR. In this cohort, 35,2% (269 of 764) the volunteers were positive for COVID-19. The prevalence of COVID-19 was higher among women (67%) and individuals aged between 18 and 49 years. Also, comorbidities as obesity and arterial hypertension were more frequent in the positive group, when considered individuals under 60 years old. Higher ACE and ACE2 enzymatic activities were observed in positive group (46.4 vs 41.6 and 11.3 vs 8.5, respectively). Individuals with ID genotype in the positive group presented higher ACE activity compared to individuals with same genotype in control group (46.9 vs 41.7). In the positive group, ACE activity was increased in the DD (54.5) when compared to ID (46.9) and II (37.9) genotypes. No significant differences related to ACE2 activity and polymorphism were observed. ACE/ACE2 activity ratio was higher in the COVID-19 negative group (4.7 vs 3.7). The increased ACE activity for the DD genotype was in line with the literature data for hypertension and cardiovascular diseases. We can suggest a synergic effect between ACE DD genotype and COVID-19 infection enhancing ACE activity, what may contribute to pro-inflammatory phenotype and more severe symptoms of COVID-19.

Abstract P165: Urinary Amino Acid Profile And Cardiovascular Parameters In Overweight And Obese Brazilian Children

Despite being thoroughly studied, there isn’t complete elucidation of mechanisms underlying obesity, and especially regarding overweight in children. Small molecule metabolites are promising candidates for understanding obesity′s phenotypes. Recent metabolic studies have advanced in discovery of biomarkers for better knowledge of mechanisms related to obesity and its comorbidities. In this cross-sectional study it was evaluated the profile of urinary amino acids of 110 children that were classified in into groups of nutritional status according to their BMI/A (Body Mass Index/age), as normal weight (NW) (n=45), overweight (OW) (n=21) and obese (OB) (n=44). The 24h urine samples were submitted to LC-MS/MS for evaluation of 47 amino acids using Amino Acids Analysis Kit (Zivak®, Turkey), corrected by creatinine concentration. Biochemical profile, cardiovascular parameters and anthropometric measurements were assessed following standard protocols. Girls showed a higher heart rate (G: 82bpm vs B:79bpm, p=0,01 ) than boys. Increased weight presented higher values of systolic blood pressure ( NW: 102.0, OW: 109.0, OB: 110.0; NW vs OW, p = 0.0001; NW vs OB, p = 0.0001 ) and diastolic blood pressure ( NW: 60.0, OW: 67.0, OB: 66.75, NW vs OW, p < 0.0001; NW vs OB, p < 0.0001 ). The following amino acids (expressed in nmol/mg of creatinine) were found in higher concentrations in children’s urine with overweight or obesity, when compared with NW group, glutamine ( NW: 1024.3 vs OW: 1309.2, p=0.05), tryptophan (NW: 85.65, OW:113.55, OB:109.36; NW vs OW p=0.01; OW vs OB p=0.004), phenylalanine (NW: 43.04, OW:49.66, OB:72.08; NW vs OB p=0.01; OW vs OB p=0.04), and Tyrosine (NW: 85.07, OW: 109.74, OB: 140.54; NW vs OB p<0.01; OW vs OB p=0.04). In contrast, sarcosine had reduced concentrations for groups with weight excess (OW: 78.7 vs OB: 62.3, p=0.04). Urine levels of glutamine and aromatic amino acids were higher in OW and OB groups. Tyrosine also showed a positive association with systolic blood pressure values. Thus, there was a positive correlation between levels of glutamine and aromatics amino acids and excess weight, suggesting that they may be candidates to biomarkers for obesity in children. Furthermore, obesity was directly related to increase in blood pressure values.

Saccharomyces boulardii modulates oxidative stress and renin angiotensin system attenuating diabetes-induced liver injury in mice

Type 1 diabetes (T1DM) is a chronic disease characterized by hyperglycemia due to a deficiency in endogenous insulin production, resulting from pancreatic beta cell death. Persistent hyperglycemia leads to enhanced oxidative stress and liver injury. Several studies have evaluated the anti-diabetic and protective effects of probiotic strains in animal models. In the present study, we investigated, through histopathological and biochemical analyses, the effects of eight weeks of administration of Saccharomyces boulardii (S. boulardii) yeast on the liver of streptozotocin (STZ) induced diabetic C57BL/6 mice. Our results demonstrated that S. boulardii attenuates hepatocytes hydropic degeneration and hepatic vessels congestion in STZ-induced diabetic mice. The treatment attenuated the oxidative stress in diabetic mice leading to a reduction of carbonylated protein concentration and increased activity of antioxidant enzymes superoxide dismutase and glutathione peroxidase, compared to untreated diabetic animals. The results also show the beneficial influence of S. boulardii in regulating the hepatic concentration of renin angiotensin system (RAS) peptides. Therefore, our results demonstrated that S. boulardii administration to STZ-induced diabetic mice reduces oxidative stress and normalizes the concentration of RAS peptides, supporting the hypothesis that this yeast may have a role as a potential adjunctive therapy to attenuate diabetes-induced liver injury.

Resistance exercise training ameliorates chronic kidney disease outcomes in a 5/6 nephrectomy model

Chronic kidney disease (CKD) is defined by decreased glomerular filtration rate (GFR) or increased albumin excretion leading to renal injury. However, exercise training is an important non-pharmacological intervention that ameliorates and protects against Diabetes Mellitus, cardiovascular disease, and CKD.

AIM

Our aim was to evaluate the capability of resistance exercise training (RET) to improve CKD outcomes and the contribution of the renal and muscular Akt/mTOR signaling pathway for RET beneficial effects on a CKD model.

MAIN METHODS

Male Wistar rats were subjected to RET, followed for 10 weeks, and randomly divided into 5 groups: Sham: Sham-operated; sedentary and nephrectomy (5/6Nx) (SNS); exercising post-5/6Nx (SNE); exercising pre-5/6Nx (ENS); exercising pre- and post-5/6Nx (ENE). The systolic blood pressure (BP) was measured. Creatinine, proteinuria, and blood urea nitrogen (BUN) were evaluated. After euthanasia Renal and muscular Akt/mTOR signaling pathways were analyzed.

KEY FINDING

Our study showed that the SNS presented renal injury, hypertension, weight and muscular mass loss and a higher mortality rate. SNS group also decreased renal IL-10 and increased TNF-alfa and TGF-Beta. Renal AKT, mTOR, and rpS6 pathway were increased, PTEN was decreased on SNS. And muscular Akt and mTOR were decreased on SNS.

SIGNIFICANCE

The RET before and after the 5/6Nx ameliorates all these parameters mentioned above, suggesting that RET is a good non-pharmacological approach to diminish complications frequently found in CKD. We also suggest that the AKT-m-TOR pathway can play an important role in these beneficial outcomes of RET on the CKD animal model.

Abstract MP25: Expression Of Urinary Somatic And Soluble N-domain Isoforms Of Angiotensin Converting Enzyme And Association With Different Nutritional Status And Cardiovascular Risk Profile

Angiotensin converting enzyme (ACE) plays a dominant role in renal and cardiovascular diseases, obesity and diabetes. The somatic ACE (130-190 kDa) is composed of two homologous N- and C- domains. Two soluble N-domain isoforms have been described in human urine with 65 and 90KDa. Studies have supported that N-domain ACE with 90KDa is a biomarker for hypertension, pre-eclampsia and inflammation. We analyzed the expression of somatic and soluble N-domain ACE isoforms in urine of children and adolescents with different nutritional status and cardiovascular risk profile. The volunteers aged from 6 to 19 years were classified into four groups according to their BMI percentile; underweight (n=51), normal weight (n = 53), overweight (n=53) and obese (n=49). Waist-height-ratio (WHtR) was used to assess cardiovascular risk profile dividing the participants into normal risk (n=105) and high risk (n=101). The urines were concentrated 10-fold and dialyzed with Tris-HCl pH 8 and pure water. Then, we performed western blot analysis using 50μg of lyophilized urinary protein, using the ACE polyclonal antibody Y1. Protein detection was performed by chemiluminescent and analysis in Image Lab software utilizing total protein stain for normalization. ACE expression is augmented in obese children when compared with normal weight children ( 0.09 vs 0.53 arbitrary units, p=0,04 ). The higher cardiovascular risk group also presented increased expression of ACE ( 0.27 vs 0.09 arbitrary units, p=0.046 ). The 90KDa N-domain isoform is frequently found in the high cardiovascular risk children ( p= 0.02 ). According to Spearman correlation test, the expression of 90 kDa N-domain ACE correlates positively with waist circumference, WHtR, BMI percentile and Z-score of BMI. Increased ACE expression in obese children contributes to higher cardiovascular risk once this enzyme biosynthesizes Angiotensin II which promotes blood pressure increase, sympathetic nervous system activation and release of glucocorticoids from adrenal gland. ACE expression is also augmented in children with high cardiovascular risk. Presence of 90 KDa N-domain ACE in urine of children and adolescents is a biomarker of poor prognostic for cardiovascular disease in childhood obesity.

Abstract P033: PRESSOR, NATRIURETIC, AND RENAL RESPONSES IN ANGIOTENSIN II-INDUCED HYPERTENSION IN MALE AND FEMALE WILD-TYPE AND PROXIMAL TUBULE-SPECIFIC AT 1A RECEPTOR KNOCKOUT MICE

Dysregulation of intrarenal renin-angiotensin system is one of the key factors of human hypertension, but the mechanisms involved remain incompletely understood. To determine the roles of AT 1a receptors in the proximal tubules of the kidney, we infused angiotensin II (Ang II) for 2 weeks (40 ng / min, i.p.) in adult male and female wild-type C57BL/6J and mutant mice with deletion of AT 1a receptors in the proximal tubules (PT- Agtr1a -/- ), and treated with or without the AT 1 receptor blocker losartan (20 mg/kg/day, p.o.) (n=8 per group). The pressor response, 24 h urinary Na + excretion, glomerular and tubulointerstitial injury were compared between male and female wild-type and PT- Agtr1a -/- mice. Basal systolic, diastolic, and mean arterial blood pressure were about 13 ± 3 mmHg lower in male and female PT- Agtr1a -/- mice ( P <0.01), but no differences were observed between male and female wild-type or PT- Agtr1a -/- mice. In response to Ang II, both male and female wild-type and PT- Agtr1a -/- mice developed hypertension ( P <0.01), and the net pressor response were similar in male and female wild-type and PT- Agtr1a -/- mice (n.s.). However, absolute blood pressure was about 12 ± 3 mmHg lower in male and female PT- Agtr1a -/- mice ( P <0.01 vs. wild-type). Ang II-induced hypertension increased the natriuretic response in both male and female wild-type and PT- Agtr1a -/- mice ( P <0.01), but there were no significant differences between male and female wild-type and PT- Agtr1a -/- mice (n.s). Losartan did not increase the natriuretic responses further in all animals. Furthermore, Ang II-induced hypertension was associated with significant increases in glomerular and tubulointerstitial injury in male and female wild-type mice ( P <0.01), which were attenuated in male and female PT- Agtr1a -/- mice ( P <0.01). LOS treatment attenuated Ang II-induced hypertension and decreased Ang II-induced glomerular and tubulointerstitial injury in male and female wild-type and PT- Agtr1a -/- mice ( P <0.01). Taken together, we demonstrated that intratubular AT 1 (AT 1a ) receptors in the proximal tubules of the kidney plays a key role in maintaining basal blood pressure homeostasis and overall body salt and fluid balance, and the development of Ang II-induced hypertension and kidney injury.

Both aldosterone and spironolactone can modulate the intracellular ACE/ANG II/AT1 and ACE2/ANG (1-7)/MAS receptor axes in human mesangial cells

The kidney is an important target of the renin‐ANG‐aldosterone system (RAAS). To date, several studies have demonstrated the existence of a local RAAS in various tissues, including the renal tissue. The mineralocorticoid aldosterone is known to play a critical role in the classical RAAS; however, its effect on mesangial cells (MCs) remains to be elucidated. Based on this, our aim was to investigate whether aldosterone stimulation can modulate the intracellular RAAS of immortalized human MCs by evaluating ANG‐converting enzyme (ACE)/ANG II/ANG II receptor type 1 (AT1) and ANG‐converting enzyme 2 (ACE2)/ANG (1‐7)/MAS receptor axes. To realise this, protein expression, enzyme activity, and immunofluorescence were performed under aldosterone stimulation and in the presence of the mineralocorticoid receptor (MR) antagonist spironolactone (SPI). We observed that high doses of aldosterone increase ACE activity. The effect of aldosterone on the catalytic activity of ACE was completely abolished with the pretreatment of SPI suggesting that the aldosterone‐induced cell injuries through ANG II release were attenuated. Aldosterone treatment also decreased the expression of MAS receptor, but did not alter the expression or the catalytic activity of ACE 2 and ANG (1‐7) levels. Spironolactone modulated the localization of ANG II and AT1 receptor and decreased ANG (1‐7) and MAS receptor levels. Our data suggest that both aldosterone and the MR receptor antagonist can modulate both of these axes and that spironolactone can protect MCs from the damage induced by aldosterone.

Inhibition of the P2X7 receptor improves renal function via renin-angiotensin system and nitric oxide on diabetic nephropathy in rats

AIM

To evaluate the effects of P2X₇ receptor blockade on renin-angiotensin system (RAS) in rats with diabetic nephropathy (DN).

MAIN METHODS

Wistar rats were unilaterally nephrectomized and received streptozotocin for diabetes mellitus (DM) induction; control animals (CTL) received the drug vehicle. The animals were submitted to P2X₇ receptor silencing, forming the group (DM + siRNA). The animals were placed in metabolic cages for data collection and evaluation of renal function; at the end of the protocol, the kidney was removed for analysis of P2X₇, renin, angiotensin-converting enzyme (ACE), ACE2, angiotensin, thiobarbituric acid reactive substance levels (TBARS), nitric oxide (NO) and qualitative histological.

KEY FINDINGS

The metabolic profile was attenuated in DM + siRNA vs. DM and there was a significant improvement in creatinine, urea and proteinuria levels in the same group. Renin expression was significantly decreased in DM + siRNA vs. DM. ACE and ACE2 were significantly reduced in DM + siRNA vs. DM. TBARS levels were decreased and NO showed an increase in DM + siRNA vs. DM, both significant. All histological alterations were improved in DM + siRNA vs. DM.

SIGNIFICANCE

Data have shown that although silencing of the P2X₇ receptor did not decrease fasting glucose, it promoted an improvement in the metabolic profile and a significant recovery of renal function, revealing a protective action by the inhibition of this receptor. This effect must have occurred due to the inhibition of RAS and the increase of NO, suggesting that the use of P2X₇ receptors inhibitors could be used as adjuvant therapy against DN progression.

Abstract P2028: Paracrine And Intracellular Angiotensin II Activate Protein Kinase C, Map Kinase Erk1/2, And Nuclear Factor-кB Signaling Responses In Murine Glomerular Mesangial Cells

The glomerular mesangial cells (MC) are a key target for the endocrine, paracrine, autocrine, and intracrine angiotensin II (ANG II). Increased local paracrine and intracrine ANG II formation in MCs may cause glomerular injury by promoting MC cell growth, hypertrophy and fibrosis. In the present study, we investigated the phospho-proteomic signaling and mitochondrial responses to paracrine or intracellular ANG II in murine MCs. MCs were grown to ~80% confluence in 6-well plates in DMEM and Ham’s F-12 medium, containing 5% fetal bovine serum and 1% penicillin-streptomycin, at 37°C under 95% O 2 /5% CO 2 . MCs were fasted in a serum-free medium for 24 h before being treated with ANG II (0.1 to 100 nM) for 5 to 60 min, or transfected with a mitochondria-targeting intracellular ANG II for 48 h (mito-ECFP/ANG II, 4 μg/well), with or without pretreatment with the AT 1 receptor blocker losartan (1 μM), AT 2 receptor blocker PD123319 (1 μM), or expression of mito-AT 2 receptors. Proteins were extracted for Western blot analysis of p-PKCα, p-ERK1/2, p38 MAPK, p65 and p50 subunits of NF-кB, or mitochondria protein complexes I to V, respectively. ANG II significantly increased p-ERK1/2 (Control: 0.20 ±0.07 vs. ANG II: 0.04 ± 0.07, p&lt0.05), p-PKCα (Control: 0.50 ± 0.10 vs. ANG II: 1.30 ±0.20, p&lt0.01), p38 MAPK (Control: 0.30 ±0.04 vs. ANG II: 0.60 ±0.06, p&lt0.01), and NF-кB responses (Control: 0.30 ±0.02 vs. ANG II: 0.55 ± 0.08, p&lt0.01) in dose- and time-dependent manners, with peak responses to ANG II occurred between 0.1 and 1.0 nM, 5-10 min ( p &lt0.05). These phopho-proteomic signaling responses were attenuated by losartan (p&lt0.01) or PD123319 (p&lt0.01), respectively. mito-ECFP/ANG II increased mitochondrial protein complex I &gt38%, Complex III &gt56%, Complex IV &gt89%, and Complex V &gt63%, respectively (p&lt0.01). The effects of mito-ECFP/ANG II on mitochondrial protein complexes were attenuated by losartan or the expression of mito-AT 2 receptors (p&lt0.01). These results suggest that paracrine and intracellular ANG II may activate AT 1 and AT 2 receptors to induce important MAP kinases ERK1/2, p-PKCα, p38 MAPK, NF-кB signaling, or mitochondria responses in MCs, which may contribute to ANG II-induced glomerular injury in hypertension and kidney diseases.

Abstract P2040: Acute Effects of Weight Loss by Dehydration on Renal Function in Mixed Martial Arts

Currently there is a significant growth in the world in the number of professional fighters and practitioners of Mixed Martial Arts. In order to promote greater preservation of the physical integrity of the athletes, weight categories were created, however some fighters in the attempt of insertion into inferior categories, use the dehydration for their drastic reduction of the weight. Hypothetically, the method used may trigger some damage to the body, such as a decrease in the volume of renal blood flow. This study aims to identify the acute effects of weight loss by dehydration on kidney function in a Mixed Martial Arts fighter. The study volunteer is MLC, 34 years old, male, black, single, natural and resident in Maceió-AL-Brazil, without metabolic diseases, with a family history of arterial hypertension. It does not use drugs or dietary supplementation. The athlete practices combat sports with participation in competitions in these three years, with an average loss of 7 kg to fight for dehydration during a month before the fights. The signature of the Free and Informed Consent Term of the athletes was collected. Three collections were carried out: one month before the fight, the official weighing day and the day of the event. According to the data presented in the present study, in response to reduction of body weight by dehydration for insertion in a lower fighting category of around 7 kg, it was observed that the athlete presented some abnormalities during the body weight loss / gain cycle as glycosuria, non-reversible positive leukocyturia and proteinuria within 24 hours, elevated serum creatinine (1.3 mg / dL) and urea (42 mg / dL) during the peak of dehydration (day of weighing and fighting). Blood ureic nitrogen / creatinine ratio (15.8) and creatinine clearance (126.1 mL / min) were elevated during the three moments of observation, namely 30 days pre-fight, day of weighing and fighting. Elevated creatinine clearance suggests renal damage with increased filtration rate with possible renal damage from dehydration. We are completing the analysis of a further 10 athletes, and our data suggest the need for guidance of these athletes so that the training method is less detrimental to their physical integrity.

Circulating catecholamines are associated with biobehavioral factors and anxiety symptoms in head and neck cancer patients

Studies have shown that stress-related catecholamines may affect cancer progression. However, little is known about catecholamine secretion profiles in head and neck cancer patients. The present study investigated plasma norepinephrine and epinephrine levels in head and neck squamous cell carcinoma (HNSCC) patients and patients with oral leukoplakia, as well as their association with clinicopathological and biobehavioral variables and anxiety symptoms. A total of 93 patients with HNSCC and 32 patients with oral leukoplakia were included. Plasma norepinephrine and epinephrine levels were measured by high performance liquid chromatography with electrochemical detection (HPLC-ED), and psychological anxiety levels were measured by the Beck Anxiety Inventory (BAI). Plasma norepinephrine and epinephrine concentrations were significantly higher in patients with oral and oropharyngeal squamous cell carcinoma (SCC) compared to non-cancer patients. Oral SCC patients displayed plasma norepinephrine levels about six times higher than oropharyngeal SCC patients, and nine times higher than oral leukoplakia patients (p < .001). Plasma epinephrine levels in oral SCC patients were higher compared to the oropharyngeal SCC (p = .0097) and leukoplakia (p < .0001) patients. Oropharyngeal SCC patients had higher plasma norepinephrine (p = .0382) and epinephrine levels (p = .045) than patients with oral leukoplakia. Multiple regression analyses showed that a history of high alcohol consumption was predictive for reduced plasma norepinephrine levels in the oral SCC group (p < .001). Anxiety symptom of “hand tremor” measured by the BAI was an independent predictor for higher plasma norepinephrine levels in HNSCC patients (β = 157.5, p = .0377), while the “heart pounding/racing” symptom was independently associated with higher plasma epinephrine levels in the oropharyngeal SCC group (β = 15.8, p = .0441). In oral leukoplakia patients, sleep deprivation and worse sleep quality were independent predictors for higher plasma norepinephrine levels, while severe tobacco consumption and higher anxiety levels were factors for higher plasma epinephrine levels. These findings suggest that head and neck cancer patients display sympathetic nervous system hyperactivity, and that changes in circulating catecholamines may be associated with alcohol consumption, as well as withdrawal-related anxiety symptoms.

The binding of captopril to angiotensin I-converting enzyme triggers activation of signaling pathways

Hypertension is a global health problem, and angiotensin I (ANG I)-converting enzyme (ACE) inhibitors are largely used to control this pathology. Recently, it has been shown that ACE can also act as a transducer signal molecule when its inhibitors or substrates bind to it. This new role of ACE could contribute to understanding some of the effects not explained by its catalytic activity only. In this study, we investigated signaling pathway activation in Chinese hamster ovary (CHO) cells stably expressing ACE (CHO-ACE) under different conditions. We also investigated gene modulation after 4 h and 24 h of captopril treatment. Our results demonstrated that CHO-ACE cells when stimulated with ANG I, ramipril, or captopril led to JNK and ERK1/2 phosphorylation. To verify any physiological role at the endogenous level, we made use of primary cultures of mesangial cells from spontaneously hypertensive rats (SHR) and Wistar rats. Our results showed that ERK1/2 activation occurred mainly in primary cultures of mesangial cells from SHR rats upon captopril stimulation, suggesting that this signaling pathway could be differentially regulated during hypertension. Our results also showed that captopril treatment leads to a decrease of cyclooxygenase 2, interleukin-1β, and β-arrestin2 and a significant increase of AP2 gene expression levels. Our findings strengthen the fact that, in addition to the blockage of enzymatic activity, ACE inhibitors also trigger signaling pathway activation, and this may contribute to their beneficial effects in the treatment of hypertension and other pathologies.

Temporal changes in cardiac oxidative stress, inflammation and remodeling induced by exercise in hypertension: Role for local angiotensin II reduction

Exercise training reduces renin-angiotensin system (RAS) activation, decreases plasma and tissue oxidative stress and inflammation in hypertension. However, the temporal nature of these phenomena in response to exercise is unknown. We sought to determine in spontaneously hypertensive rats (SHR) and age-matched WKY controls the weekly effects of training on blood pressure (BP), plasma and left ventricle (LV) Ang II and Ang-(1–7) content (HPLC), LV oxidative stress (DHE staining), gene and protein expression (qPCR and WB) of pro-inflammatory cytokines, antioxidant enzymes and their consequence on hypertension-induced cardiac remodeling. SHR and WKY were submitted to aerobic training (T) or maintained sedentary (S) for 8 weeks; measurements were made at weeks 0, 1, 2, 4 and 8. Hypertension-induced cardiac hypertrophy was accompanied by acute plasma Ang II increase with amplified responses during the late phase of LV hypertrophy. Similar pattern was observed for oxidative stress markers, TNF alpha and interleukin-1β, associated with cardiomyocytes’ diameter enlargement and collagen deposition. SHR-T exhibited prompt and marked decrease in LV Ang II content (T₁vs T₄ in WKY-T), normalized oxidative stress (T₂), augmented antioxidant defense (T₄) and reduced both collagen deposition and inflammatory profile (T₈), without changing cardiomyocytes’ diameter and LV hypertrophy. These changes were accompanied by decreased plasma Ang II content (T₂-T₄) and reduced BP (T₈). SHR-T and WKY-T showed parallel increases in LV and plasma Ang-(1–7) content. Our data indicate that early training-induced downregulation of LV ACE-AngII-AT1 receptor axis is a crucial mechanism to reduce oxidative/pro-inflammatory profile and improve antioxidant defense in SHR-T, showing in addition this effect precedes plasma RAS deactivation.

(Pro)renin receptor expression in myocardial infarction in transgenic mice expressing rat tonin

The (pro)renin receptor [(P)RR] has been implicated as a renin/prorenin receptor, and plays a role in local renin angiotensin system activation. Our goal was to investigate whether a transgenic mouse that expresses rat tonin [TGM'(rTon)] can regulate (P)RR mRNA levels. Control (C) and TGM'(rTon) animals were subdivided into the C sham, C MI, TGM'(rTon) sham, and TGM'(rTon) MI groups. The levels of tonin, (P)RR, and renin were determined using RT-PCR mRNA. Tonin activity as determined by RIE was significantly increased in the TGM'(rTon) sham group as compared to the C sham group in the atrium (AT) and right ventricle (RV), respectively. In most mice, tonin mRNA levels were significantly reduced compared to those in the TGM'(rTon) sham group in the atria. In this structure, the (P)RR mRNA levels were statistically significantly reduced in the TGM'(rTon) sham and TGM'(rTon) MI groups compared to the control groups. However, the (P)RR mRNA values were significantly increased when we compared the TGM'(rTon) MI vs TGM'(rTon) sham groups. In the RV, the renin mRNA levels in the TGM'(rTon) sham group were significantly reduced compared to the C sham group. Tonin overexpression may act in the regulation of (P)RR mRNA levels during MI.

Abstract P311: Intracellular Renin Angiotensin Aldosterone System inMesangial Cells Under the Stimulus of Aldosterone

Mesangial cells (MCs) are a local target for aldosterone (aldo) action in the modulation of the renin angiotensin aldosterone system (RAAS).Its molecular mechanisms is far from clear, and are extremely important in understanding renal pathologies. We investigated if the effect of aldosterone stimulus in supra, physiological and sub physiological doses was able to modulate the intracrine human MCs RAAS. We performed viability assays, western blot, immunofluorescence, ACE and ACE2 activities. As a result, we have obtained that the ACE activity was increased after MCs treatment with aldosterone 1 and 10 nM when compared with 0.1nM after 72h. Previous cells treatment with spirolactone followed by aldo reduced ACE catalytic activity but not ACE2. ACE and ACE 2 expression increased after 72h of MCs treatment with aldo 10 nM. The immunofluorescence showed that ACE was overexpressed in MCs after 72h with 10nM aldosterone treatment being similar to control group, differing from the treatment with spirolactone + aldo stimulation that decreased ACE expression, internalized Angiotensin II and changed the AT1 receptor localization. The same treatment increased MAS receptor production in MCs after 72h of aldosterone treatment with 10, 1.0, 0.1 and 0.01nM , but not with spirolactone + aldo treatment that inhibited receptor synthesis. ACE2 was detected in cell nucleus with 24h of treatment with aldo and in cytoplasm after 72h, being reduced after the treatment with spirolactone+aldo. Ang 1-7 was localized at cell nucleus and in cytoplasm after treatment with aldo 24h and 72h, decreasing with spirolactone + aldo treatment. Immunofluorescence results demonstrated that MCs pre-treated with spironolactone decreased ACE, ACE2 and MAS receptor expression, and altered ANG II localization, suggesting that spironolactone acts on the mineralocorticoid receptor internalizing ANG II into the nucleus, probably by AT1 and AT2 receptors pathways. These results demonstrated that aldosterone can modulate the local RAAS in mesangial cells suggesting that its physiological concentrations are necessary for the feasibility of these cells while high doses are cytotoxic and altered the local system.

Association between Diastolic Dysfunction with Inflammation and Oxidative Stress in Females ob/ob Mice

Objective: To evaluate autonomic and cardiovascular function, as well as inflammatory and oxidative stress markers in ob/ob female mice.

Methods: Metabolic parameters, cardiac function, arterial pressure (AP), autonomic, hormonal, inflammatory, and oxidative stress markers were evaluated in 12-weeks female wild-type (WT group) and ob/ob mice (OB group).

Results: OB animals showed increased body weight, blood glucose, and triglyceride levels, along with glucose intolerance, when compared to WT animals. Ejection fraction (EF) and AP were similar between groups; however, the OB group presented diastolic dysfunction, as well as an impairment on myocardial performance index. Moreover, the OB group exhibited important autonomic dysfunction and baroreflex sensitivity impairment, when compared to WT group. OB group showed increased Angiotensin II levels in heart and renal tissues; decreased adiponectin and increased inflammatory markers in adipose tissue and spleen. Additionally, OB mice presented a higher damage to proteins and lipoperoxidation and lower activity of antioxidant enzymes in kidney and heart. Correlations were found between autonomic dysfunction with angiotensin II and inflammatory mediators, as well as between inflammation and oxidative stress.

Conclusions: Our results showed that female adult ob/ob mice presented discrete diastolic dysfunction accompanied by autonomic disorder, which is associated with inflammation and oxidative stress in these animals.

90-kDa N-domain angiotensin I-converting enzyme (ACE): possible marker for hypertension in a renal transplant model

INTRODUCTION

Hypertension is nearly universal in kidney transplant and several factors are associated with post transplant hypertension, including immunosuppressive medications and genetic predisposition.

OBJECTIVE

The aims were to evaluate the effects of spontaneously hypertensive rats (SHR) kidney transplantation in Wistar rats and the possible transference of 80/90-kDa N-domain ACE.

METHODS

To do so, the data from Wistar recipients of kidney from SHR were compared to data from transplanted Wistar submitted to CsA treatment and, to Wistar Sham.

RESULTS AND DISCUSSION

Despite the unaltered blood pressure observed at early stages, 80/90-kDa ACE was found expressed in the urine of rats 7 and 15 days after transplantation, which was intense when rats became hypertensive 30 days post-surgery.

CONCLUSION

Our data show that this enzyme is associated with the development of hypertension, and this marker appears in the urine before any substantial blood pressure alteration.

Abstract P633: Resistance Training Counteracts The Systemic Catecholaminergic Hyperactivation Associated With Experimental Diabetes, But Not Normalize Cardiac Sympathetic Outflow

Previous studies from our laboratory have demonstrated that chronic diabetes in rats results in cardiomyopathy, associated with sympathetic nervous system (SNS) hyperactivity. On the other hand, it is well known that the beneficial cardiovascular effects of exercise training in diabetes are due in part to normalization of the sympathetic outflow and improvement in the responsiveness of the myocardium to autonomic stimulation. Recently, resistance training (RT) has been recognized as a useful therapeutic tool for the treatment of chronic diseases and similar to aerobic exercise, has been reported to improve metabolic profile and body composition. Therefore, the aim of this study was to evaluate the effect of moderate-intensity RT on circulating and cardiac catecholamines concentration, to understand whether this type of exercise is also associated with cardiovascular protection. Wistar rats (3 months old) were randomized into: control (C), diabetic (D), diabetic + RPT (DR) and diabetic + APT (DA). Animals were made diabetic with a single tail injection of streptozotocin (STZ, 50 mg/Kg). Resistance exercise training was performed on a vertical ladder (5 days/week, 8 weeks) at 40-60% maximal load, and moderate aerobic training was performed on a treadmill (5 days/week, 8 weeks). Diabetes significantly increased plasma concentration of adrenaline (D: 5.3 ± 1.0 vs. C: 4.1 ± 0.6 ng/mL) and noradrenaline (D: 14.5 ± 0.2 vs. C: 3.1± 0.8 ng/mL), and both exercise modalities induced a significant reduction of them: adrenaline (DR: 1.1 ± 0.3; DA: 0.7 ± 0.16 vs. D: 5.3 ± 1.0 ng/mL) and noradrenaline (DR: 1.0 ± 0.2; DA: 0.7 ± 0.1 vs. D: 14.5 ± 0.2 ng/mL). Cardiac concentration of noradrenaline was also increased in diabetic group (D: 62 ± 7 vs. CS: 34 ± 6 pg/g) and only aerobic exercise was capable to reduce its concentration in heart tissue (DA: 30 ± 6 vs. D: 62 ± 7; DR: 55 ± 7 pg/g). The results from the present study show for the first time additional beneficial effects of RT on modulating SNS activity in diabetes. Moreover, considering that RT does not modulate cardiac catecholaminergic secretion, it also highlights the importance of aerobic training in diabetes treatment. Financial Support: FAPESP, CAPES, CNPq

Abstract P286: Modulation Way Classical and Alternatives of Renin Angiotensin System (RAS) in Mesangial Cells After Exposure to Fructose

Background: Our group demonstrated previously that rats subjected to a high fructose diet showed increased activity of kidney ACE.In order to understand the effect of fructose in the forming process of angiotensin II (AngII) and angiotensin 1-7 (Ang1-7) affecting the levels of these effectors, the aim of this study was to evaluate the activities of the RAS enzymes responsible for the formation of Ang1-7 and AngIIof immortalized human mesangial cells (IMCH)exposed to low and high concentration of fructose.

Methods: IMCH were divided into control (low glucose medium), Fructose 5 mM(medium + 5 mM Fructose) and Fructose 30mM(medium + 30 mM Fructose) groups. The enzymatic activity of ACE, chymase, cathepsin D, Neutral Endopeptidase (NEP) and ACE2 were evaluated using Z-Phe-His-Leu,Abz-AIKFFSAQ-EDDnp, Abz-AIAFFSRQ-EDDnp,Abz(d)-Arg-Gly-Leu,Mca-APK (DNP) as substrates respectively. Data were analyzed using ANOVA one way.

Results: Among the AngIIforming enzymes, fructose decreased ACE activity in cell lysate.Both fructose concentrations increased chymase in the culture medium. No effect was observed on the activity of cathepsin D. When evaluating the activities of peptidases forming Ang-1-7,NEP activity was increasedin culture medium.We did not detected differences in ACE2 activity.

Conclusion: The results suggest fructose modulates renal and systemic RAS in IMCH acting in the classical andalternative pathways of AngII formation. Additionally this sugar was able to increase NEP activity, forming Ang-1-7. Quantitation of angiotensin remains necessary to better understand how the end effector is available in IMCH and evaluate possible effects on glomerular physiology.

Abstract P634: Aerobic Training Prevents The Development Of Metabolic Abnormalities Induced By Chronic Stress, But Not Abnormal Circulating Levels Of Noradrenaline And Serotonin

The chronic mild and unpredictable stress (CMS) protocol induces insulin resistance, dyslipidemia, oxidative stress and endothelial dysfunction in rats. Regular physical exercise is an effective non-pharmacological tool for the treatment of disorders induced by stress. The aim was to evaluate the role of physical training on hormonal and metabolic changes triggered by CMS. Forty male Sprague-Dawley rats were randomized into: Control, Stress, Exercise, Exercise + Stress, submitted to CMS protocol or to 8-week treadmill training (50-70% of the maximal exercise test). In the 4 th , 5 th and 6 th wk, the animals were submitted to CMS protocol over seven days, repeating the procedures for 3 consecutive weeks. Two weeks after last stressor stimulus, blood and left ventricle were collected. Physical performance of animals submitted to the CMS was lower when compared to control animals, and physical training has not been able to alleviate this loss (p<0.05). The exercise prevented the development of metabolic changes induced by CMS, reducing hyperinsulinemia (Stress: 1.7±0.1 vs. Exercise: 1.4±0.1; Exercise + Stress: 1.3±0.1; Control: 1.4±0.0 ng/mL), insulin resistance index (Stress: 9.2±0.3 vs. Exercise: 7.1±0.2; Exercise + Stress: 5.8±0.2; Control: 8.1±0.2) and serum free fatty acids (Stress: 311.9±10.0 vs. Exercise: 193.0±16.7; Exercise + Stress: 251.6±14.16; Control: 190.1±17.3 mg/dL, p<0.05). In addition, it was also capable of reducing the cardiac concentration of serotonin (Stress: 3.1±0.1 vs. Exercise: 0.6±0.1; Exercise + Stress: 0.5±0.0; Control: 1.3±0.1 pg/g, p<0.05) of stressed animals (CMS). Physical training did not reduce the circulating concentration of noradrenaline (Stress: 603.7±52.2; Exercise: 83.8±10.8; Exercise + Stress: 748.9±46.1 vs. Control: 165.1±27.1 pg/mL) and serotonin (Stress: 1296.0±47.0; Exercise: 1196.0±68.1; Exercise + Stress: 1736.0±60.12 vs. Control: 619.8±79.6), which remained high in the groups submitted to the CMS (p>0.05). The results show that exercise improves metabolic losses triggered by CMS, but not the but not abnormal circulating levels of noradrenaline and serotonin, and suggest that physical training must be prescribed with caution to stressed individuals.

Plasma proteomics for the assessment of acute renal transplant rejection

Renal transplant is the best treatment for patients with chronical kidney disease however acute graft rejection is the major impediment to success in renal transplantation leading to loss of the organ the first year after transplantation. The aim of this study was to identify plasma proteins that may be early biomarkers of acute rejection of renal allograft, developing a diagnostic model that avoids the loss of the transplanted organ. Shotgun proteomics (LC-MS/MS) method was used to analyze a set of thirty-one plasma samples, including 06 from patients with acute graft rejection after transplantation (rejection group/Rej-group) and twenty-five from renal transplant patients with stable renal graft function (control group/Ct-group). As results nineteen proteins were upregulated in the rejection group compared to the control group, and two proteins were downregulated; and three were present exclusively in the rejection group. After analysis, we selected four proteins that were related to the acute phase response and that were strongly associated with each other: they are alpha-1 antitrypsin (A1AT), alpha-2 antiplasmin (A2AP), serum amyloid A (SAA) and apolipoprotein CIII (APOC3). We think that simultaneous monitoring of SAA and APOC3 can provide insights into a broad profile of signaling proteins and is highly valuable for the early detection of a possible acute renal graft rejection.

STATEMENT OF SIGNIFICANCE OF THE STUDY

In this study we did plasma shotgun patients with and without acute rejection of renal allograft. In a clinical setting an acute rejection is typically suspected upon an increase in plasma creatinine and renal biopsy. But these methods are late and unspecific; sometimes the rejection process is already advanced when there is an increase in serum creatinine. Therefore, it is necessary to find proteins that can predict the allograft rejection process. In our study were able to identify changes in the concentration of plasma protein belonging to a network of protein interaction processes the acute phase response. We believe, therefore, that development of a routine diagnosis of these proteins can detect early acute rejection of renal allograft process, thus preventing its loss.

Reactive oxygen species contribute to dysfunction of bone marrow hematopoietic stem cells in aged C57BL/6 J mice

Background

Stem cells of intensely regenerative tissues are susceptible to cellular damage. Although the response to this process in hematopoietic stem cells (HSCs) is crucial, the mechanisms by which hematopoietic homeostasis is sustained are not completely understood. Aging increases reactive oxygen species (ROS) levels and inflammation, which contribute to increased proliferation, senescence and/or apoptosis, leading to self-renewal premature exhaustion. In this study, we assessed ROS production, DNA damage, apoptosis, senescence and plasticity in young, middle and aged (2-, 12- and 24-month-old, respectively) C57BL/6 J mice.

Results

Aged HSCs showed an increase in intracellular superoxide anion (1.4-fold), hydrogen peroxide (2-fold), nitric oxide (1.6-fold), peroxynitrite/hidroxil (2.6-fold) compared with young cells. We found that mitochondria and NADPHox were the major sources of ROS production in the three groups studied, whereas CYP450 contributed in middle and aged, and xanthine oxidase only in aged HSCs. In addition, we observed DNA damage and apoptosis in the middle (4.2- and 2-fold, respectively) and aged (6- and 4-fold, respectively) mice; aged mice also exhibited a significantly shorter telomere length (−1.8-fold) and a lower expression of plasticity markers.

Conclusion

These data suggest that aging impairs the functionality of HSCs and that these age-associated alterations may affect the efficacy of aged HSC recovery and transplantation.

Aldosterone Contributes to Sympathoexcitation in Renovascular Hypertension

BACKGROUND

Although angiotensin II (Ang II) is essential to the development of renovascular hypertension, aldosterone plays a role as well. Recent studies have demonstrated a cross-talk between Ang II type 1 and mineralocorticoid receptors in the brain and kidneys. However, the role of aldosterone in the autonomic and renal dysfunction of renovascular hypertension is not well understood.

AIM

The current study evaluated whether aldosterone contributes to cardiovascular and renal dysfunction in the 2 kidney-1 clip (2K1C) model.

METHODS

Mean arterial pressure (MAP) and baroreceptor reflex for control of the heart rate were evaluated in 2K1C treated or not treated with spironolactone (200mg/kg/day, 7 days). Tonic and reflex control of renal sympathetic nerve activity (rSNA) were assessed in urethane-anaesthetized rats. Plasma renin activity (PRA), kidney renin protein expression, renal injury, and central AT1 receptor protein expression were assessed.

RESULTS

Spiro reduced MAP (198±4 vs. 170±9mm Hg; P < 0.05), normalized rSNA (147±9 vs. 96±10 pps; P < 0.05), and increased renal baroreceptor reflex sensitivity in the 2K1C rats. Spiro reduced α-smooth muscle actin expression in the nonclipped kidney in the 2K1C group (5±0.6 vs. 1.1±0.2%; P < 0.05). There was no change in PRA; however, a decrease in renin protein expression in the nonclipped kidney was found in the 2K1C treated group (217±30 vs. 160±19%; P < 0.05). Spiro treatment decreased AT1 receptor in the central nervous system (CNS) only in 2K1C rats (138±10 vs. 84±12%; P < 0.05).

CONCLUSION

Aldosterone contributes to autonomic dysfunction and intrarenal injury in 2K1C, these effects are mediated by the CNS.

Abstract P104: Renin Angiotensin System (RAS) Modulation in Hypertension Program by Maternal Intrauterine Malnutrition

Intrauterine malnutrition (IM) during the early stages of development can alter the function of organs and tissues and can predict a lifetime of increased risk for adverse health outcomes, such as diabetes and hypertension. The kidney plays a key role in the development of hypertension programmed by IM, with the participation of the RAS. Our objectives were to study ACE activity and angiotensin peptides levels in tissues. Pregnants Wistar rats were separated into two groups: control group (C), fed ad libitum, and malnourished group (D) submitted to food restriction (diet 50% of the amount of feed consumed by the group C). After birth the offspring were kept as experimental groups C and D, respectively. At 4 months of age, the animals were sacrificed, heart and kidney tissues were collected to quantify angiotensin peptides and ACE activity. The offspring born with low birth weight. Kidney ACE activity was higher in group D compared to group C (299 ±86.7 vs. 253.4 ±84.82 mU/mg, p<0.05), differing from Heart (D versus C: 0.15 ± 0.08 vs. 0.24 ±0.09 mU/mg). Group D presented high blood pressure values compared to group C (140.6 ±2.8 vs. 124,3±2.6 mmHg). Kidney and heart Ang II levels were increased in group D being significant when compared to group C (238.26 ±25.1 vs. 161.85 ±45.6 pmol/g and 397.89±74.9 vs. 223.33±48.7 pmol/g, p<0.05, respectively). The same was observed for Ang I. The vasodilator peptide Ang1-7 levels in group D from kidney and heart were lower in comparison with group C, thus emphasizing an enabling environment for hypertension (220.74 ± 48.74 vs. 288.09 ± 47 pmol/g and 152.1±41.2 pmol/g vs. 228.93±41.2 pmol/g, p<0.05, respectively). Our results indicate that perturbed maternal nutritional status alters tissue RAS resulting in higher blood pressure in the offspring, demonstrated by increased renal ACE activity and Ang II levels, with reduced Ang 1-7. The increase of Ang I and II in the heart, despite low ACE activity in this tissue suggests the activation of RAS alternative pathways. This study describes for the first time that low levels of Ang 1-7 contributed to the early development of hypertension.

Characterization of the renal renin-angiotensin system in transgenic mice that express rat tonin

INTRODUCTION

Tonin is an enzyme that is able to generate angiotensin II (Ang II) from angiotensin I (Ang I) or directly from angiotensinogen. Our goal was to characterize the renal renin-angiotensin system in transgenic mice that express rat tonin (TGM`(rTon)).

MATERIALS AND METHODS

Mice were euthanized and the kidneys removed for analysis. Tonin activity was evaluated by radioimmunoassay and angiotensin I-converting enzyme (ACE) activity by HPLC. Tonin, ACE and angiotensin II-converting enzyme (ACE2) expression was analyzed by Western blotting.

RESULTS

Tonin activity was significantly increased in TGM`(rTon) compared to their respective wild-type (WT) littermates (1.7 ± 0.21 vs 0.11 ± 0.02 nmol of Ang II/min/mg of protein). Tonin activity had a strong positive correlation with tonin expression in both TGM`(rTon) and their respective wild-type littermates. The ACE activity and expression levels of 65-kDa N-domain angiotensin I-converting enzyme isoform were significantly increased in the TGM`(rTon) when compared with WT. ACE2 expression levels were statistically significantly higher in the TGM`(rTon) when compared with WT. Angiotensin 1-7 (Ang(1-7)) and Ang I levels were significantly lower in the TGM`(rTon).

CONCLUSIONS

We suggest that the environment of tonin abundance may increase N-domain ACE activity liberated by a secretase able to cleave somatic ACE.

Post-Exercise Hypotension and Its Mechanisms Differ after Morning and Evening Exercise: A Randomized Crossover Study

Post-exercise hypotension (PEH), calculated by the difference between post and pre-exercise values, it is greater after exercise performed in the evening than the morning. However, the hypotensive effect of morning exercise may be masked by the morning circadian increase in blood pressure. This study investigated PEH and its hemodynamic and autonomic mechanisms after sessions of aerobic exercise performed in the morning and evening, controlling for responses observed after control sessions performed at the same times of day. Sixteen pre-hypertensive men underwent four sessions (random order): two conducted in the morning (7:30am) and two in the evening (5pm). At each time of day, subjects underwent an exercise (cycling, 45 min, 50%VO₂peak) and a control (sitting rest) session. Measurements were taken pre- and post-interventions in all the sessions. The net effects of exercise were calculated for each time of day by [(post-pre exercise)-(post-pre control)] and were compared by paired t-test (P<0.05). Exercise hypotensive net effects (e.g., decreasing systolic, diastolic and mean blood pressure) occurred at both times of day, but systolic blood pressure reductions were greater after morning exercise (-7±3 vs. -3±4 mmHg, P<0.05). Exercise decreased cardiac output only in the morning (-460±771 ml/min, P<0.05), while it decreased stroke volume similarly at both times of day and increased heart rate less in the morning than in the evening (+7±5 vs. +10±5 bpm, P<0.05). Only evening exercise increased sympathovagal balance (+1.5±1.6, P<0.05) and calf blood flow responses to reactive hyperemia (+120±179 vs. -70±188 U, P<0.05). In conclusion, PEH occurs after exercise conducted at both times of day, but the systolic hypotensive effect is greater after morning exercise when circadian variations are considered. This greater effect is accompanied by a reduction of cardiac output due to a smaller increase in heart rate and cardiac sympathovagal balance.

Structural libraries of protein models for multiple species to understand evolution of the renin-angiotensin system

The details of protein pathways at a structural level provides a bridge between genetics/molecular biology and physiology. The renin-angiotensin system is involved in many physiological pathways with informative structural details in multiple components. Few studies have been performed assessing structural knowledge across the system. This assessment allows use of bioinformatics tools to fill in missing structural voids. In this paper we detail known structures of the renin-angiotensin system and use computational approaches to estimate and model components that do not have their protein structures defined. With the subsequent large library of protein structures, we then created a species specific protein library for human, mouse, rat, bovine, zebrafish, and chicken for the system. The rat structural system allowed for rapid screening of genetic variants from 51 commonly used rat strains, identifying amino acid variants in angiotensinogen, ACE2, and AT1b that are in contact positions with other macromolecules. We believe the structural map will be of value for other researchers to understand their experimental data in the context of an environment for multiple proteins, providing pdb files of proteins for the renin-angiotensin system in six species. With detailed structural descriptions of each protein, it is easier to assess a species for use in translating human diseases with animal models. Additionally, as whole genome sequencing continues to decrease in cost, tools such as molecular modeling will gain use as an initial step in designing efficient hypothesis driven research, addressing potential functional outcomes of genetic variants with precompiled protein libraries aiding in rapid characterizations.

Cecropia pachystachya extract attenuated the renal lesion in 5/6 nephrectomized rats by reducing inflammation and renal arginase activity

ETHNOPHARMACOLOGICAL RELEVANCE

The plant Cecropia pachystachya Trécul has been used in Brazilian folk medicine to treat hypertension, bladder and kidney inflammation and renal diseases. The aim of this study was to evaluate the potential of the aqueous fraction from the ethanolic extract of Cecropia pachystachya (FCP) in the management of hypertension, inflammation and progressive renal disease in rats submitted to 5/6 nephrectomy.

MATERIALS AND METHODS

Thirty male Wistar rats submitted to 5/6 nephrectomy (5/6 NE) were untreated (NE) or treated (NE+FCP) with the FCP (0.5g/kg/day). The treatment started 15 days after surgery, and the rats were followed for a period of 60 days. Systolic blood pressure (SBP) and albuminuria were evaluated from 15-60 days after the surgical procedure. Function and estructural renal changes, TGF-β (transforming growth factor β), MCP-1 (monocyte chemoattractant protein-1) and nitric oxide (NO) urinary excretion were analyzed. Expression and activity of the renal enzymes arginase (ARG), angiotensin converting enzyme (ACE), and MAP kinase p-JNK expression also were analyzed.

RESULTS

The nephrectomized rats developed progressive albuminuria and increased SBP that was less intense in the treated group. There was a reduction in the glomerular filtration rate (GFR) in the nephrectomized rats, which was attenuated by treatment with FCP extract. The treatment with FCP also attenuated the histological changes, reduced the expression and activity of renal arginase, the number of macrophages (ED-1 positive cells) and the p-JNK expression in the renal cortex of the rats submitted to 5/6 NE. The urinary excretion of TGF-β was less intense in the treated group and was associated with the reduction of the expression and activity of the renal arginase.

CONCLUSIONS

These results suggest that the reduction of renal arginase activity, p-JNK and TGF-β expression can explain the mechanism by which the treatment with C. pachystachya reduced the inflammation and improved renal function. This study presents the potential use of Cecropia pachystachya in the treatment of chronic renal diseases.

Angiotensin Converting Enzyme 90 kDa isoform: Biomarker for diagnosis of preeclampsia?

Preeclampsia (PE), one of the leading gestational hypertensive diseases, is characterized by increased blood pressure (⩾140/90mmHg) and pathological proteinuria after 20weeks gestation. It is a complex, multifactorial syndrome with an unestablished etiology and cure. The search continues for a biomarker that could assist in the early prediction or diagnosis of PE, reducing the rate of maternal and fetal mortality. Based on the findings of Casarini et al. that suggest the 90kDa isoform of the Angiotensin Converting Enzyme (ACE) as a possible marker of hypertension, we hypothesized that this isoform may be present in pregnant women with PE, since they present a transient and spontaneous model of systemic arterial hypertension in pregnancy. We believe, therefore, that pregnant women with pure PE (PPE) express the ACE 90kDa isoform in urine, as well as having elevated isoform enzymatic activity, during pregnancy only. Postpartum, with the normalization of blood pressure, the protein isoform would no longer be expressed. Pregnant women with superimposed preeclampsia (SPE) would present the ACE 90kDa isoform both during and after the gestation period, and its enzymatic activity would remain high as they are chronically hypertensive. It is expected that normotensive pregnant women do not present this isoform in their urine as elevated blood pressure levels do not occur. Both normotensive and PPE affected pregnant women with a family history of hypertension, will possibly express the ACE 90kDa isoform before pregnancy and may become hypertensive, only after some years, through the influence of environmental factors and/or other diseases. If our hypothesis is confirmed, it will allow differentiation of PPE and SPE sooner than 12weeks postpartum, which is currently the estimated period for confirmation of the specific diagnosis. Furthermore, it could be an early biomarker for predicting the disease, enabling the physician to choose the best clinical management. In addition, it would minimize the use of other methods as the biological sample for obtaining the marker is urine, a practical and effective test with good reproducibility. Finally, test results would enable a greater understanding of the mechanisms involved in gestational hypertension.

Inhibition of phosphodiesterase 5 restores endothelial function in renovascular hypertension

Background

The clipping of an artery supplying one of the two kidneys (2K1C) activates the renin-angiotensin (Ang) system (RAS), resulting in hypertension and endothelial dysfunction. Recently, we demonstrated the intrarenal beneficial effects of sildenafil on the high levels of Ang II and reactive oxygen species (ROS) and on high blood pressure (BP) in 2K1C mice. Thus, in the present study, we tested the hypothesis that sildenafil improves endothelial function in hypertensive 2K1C mice by improving the NO/ROS balance.

Methods

2K1C hypertension was induced in C57BL/6 mice. Two weeks later, they were treated with sildenafil (40 mg/kg/day, via oral) or vehicle for 2 weeks and compared with sham mice. At the end of the treatment, the levels of plasma and intrarenal Ang peptides were measured. Endothelial function and ROS production were assessed in mesenteric arterial bed (MAB).

Results

The 2K1C mice exhibited normal plasma levels of Ang I, II and 1–7, whereas the intrarenal Ang I and II were increased (~35% and ~140%) compared with the Sham mice. Sildenafil normalized the intrarenal Ang I and II and increased the plasma (~45%) and intrarenal (+15%) Ang 1–7. The 2K1C mice exhibited endothelial dysfunction, primarily due to increased ROS and decreased NO productions by endothelial cells, which were ameliorated by treatment with sildenafil.

Conclusion

These data suggest that the effects of sildenafil on endothelial dysfunction in 2K1C mice may be due to interaction with RAS and restoring NO/ROS balance in the endothelial cells from MAB. Thus, sildenafil is a promising candidate drug for the treatment of hypertension accompanied by endothelial dysfunction and kidney disease.

Abstract 315: Endothelial And Autonomic Dysfunctions Induced By High Fructose Intake Are Modulated By The Angiotensin Converting Enzyme (ACE) Gene Dosage

ACE gene polymorphism may be associated with different responses to physiological and pathological stimuli. Therefore, we tested whether low, normal or high levels of ACE gene dosage influence on the effects of chronic and excessive fructose intake (F).

Male mice (22±1g) harboring 1, 2 or 3 copies of the ACE gene received F (100g/l) or tap water for 8 weeks. After this period, glucose tolerance (0-120 min after glucose load=1.5 g/Kg ip) and lipids were measured; blood pressure (BP) signals were recorded (Windaq, 4kHz), and BP variability was analyzed in frequency domain (FFT). After euthanasia, mesenteric resistance artery (MRA) was dissected out and rings were mounted in an isometric myograph (DMT,620M). MRA responses to noradrenaline (Nor; 0.1nM-1μM) and acetylcholine (Ach; 0.01nM-30μM) were studied. One-way ANOVA and p<0.05 were used for statistical analysis

F induced glucose intolerance (1 copy: 100±3 vs. F=198±5; 2 copies: 121±4 vs. F=201±8; 3 copies: 86±4 vs. F=212±5 mg/dl after 120 min) with no alterations in total cholesterol nor triglycerides. Systolic BP increased in 2 and 3-copy mice after F (1 copy: 119±2 vs. F=124±4; 2 copies: 120±3 vs. F=131±3; 3 copies: 121±3 vs. F=139±4 mmHg) and diastolic BP increased in all F-fed groups (1 copy: 80±2 vs. F=92±3; 2 copies: 83±2 vs. F=95±4; 3 copies: 84±2 vs. F=100±2 mmHg). The augment in systolic BP was significantly higher in 3-copy (17±1 mmHg) vs. 1 (6±1 mmHg) and 2-copy mice (10±1 mmHg). F also increased BP variability in all groups, with a more pronounced augment in 3-copy mice vs. other groups (1 copy: 39±3 vs. F=57±2; 2 copies: 37±2 vs. F=60±3; 3 copies: 40±3 vs. F=73±7 mmHg 2 ). Additionally, the sympathetic component of BP variability (LF %) presented a similar behavior (1 copy: 5±1 vs. F=12±3; 2 copies: 6±2 vs. F=19±3; 3 copies: 7±3 vs. F=31±5 %). Ach-induced relaxation was reduced in F mice (1 copy: 78 vs. F=58; 2 copies: 76 vs. F=47; 3 copies: 73 vs. F=36 %) and a hyperreactivity to Nor was also observed (1 copy: 92 vs. F=170; 2 copies: 107 vs. F=190; 3 copies: 101 vs. F=214 %). In both responses, 3-copy mice were significantly different than the other groups.

ACE gene dosage seems to modulate the magnitude of MRA and autonomic dysfunctions caused by F consumption, inducing a more increased cardiovascular risk for 3-copy mice.

Abstract 623: Upregulation of Renin-Angiotensin System and Inflammatory Mechanisms in the Prenatally Programmed Hypertension

Strong evidence shows that renin-angiotensin system (RAS) is affected by adverse maternal nutrition during pregnancy. Early treatment of offspring with RAS inhibitors is able to prevent the development of prenatally programmed hypertension. The aim of this study was to evaluate renal RAS activity and inflammatory mechanisms and the effects of RAS inhibition in prenatally programmed hypertension. Sprague-Dawley rats were fed with standard diet (control group) or low protein (LP) diet during the period of pregnancy. After birth, dams were switched back to standard rat chow. After weaning, LP pups were randomized to either no treatment or to treatment with losartan. LP offspring presented lower birth weight when compared to CT group (5.3 ± 0.1 vs 6.4 ± 0.2 g, respectively, p<0.05). At 20 weeks of life, blood pressure levels were higher in the untreated LP group when compared to CT group (128.5 ± 0.9 vs 109.2 ± 1.9 mmHg, respectively, p<0.05). We also observed adverse histological features in the kidney of untreated LP animals when compared to CT group, including augmentation of relative interstitial area (9.27 ± 0.32 vs 3.86 ± 0.27 %, respectively, p<0.05), collagen concentration (3.53 ± 0.87 vs 0.68 ± 0.19%, respectively, p<0.05) and number of PCNA positive cells (7.36 ± 1.82 vs 1.95 ± 0.15 cells/0.274 mm2, respectively, p<0.05). Untreated LP group also had higher number of CD3 and CD68 positive cells in the kidney compared to CT group [CD3: 9.3 ± 0.5 vs 5.1 ± 0.3 cells/0.274 mm2 and CD68: 13.5 ± 1.0 vs 8.2 ± 0.9 cells/0.274 mm2, respectively, p<0.05), and higher levels of reactive oxygen species (3.6 ± 0.4 vs 1.7 ± 0.2 mmol/mg, respectively, p<0.05). In addition, renal levels of angiotensin II (Ang II) were higher in the untreated LP offspring compared to CT group (p<0.05), and inhibition of RAS was able to prevent renal injury and abolished infiltration of inflammatory cells, besides its hemodynamics benefits. The finding of high renal levels of Ang II associated with increased inflammatory infiltration and deleterious histological outcomes and the effectiveness of RAS inhibition in prevent them indicate that RAS, via Ang II/AT1 receptor, is responsible for initiating and perpetuating the inflammatory and fibrotic processes in the prenatally programmed kidney.

Upregulation of ERK1/2-eNOS via AT2 receptors decreases the contractile response to angiotensin II in resistance mesenteric arteries from obese rats

It has been clearly established that mitogen-activated protein kinases (MAPKS) are important mediators of angiotensin II (Ang II) signaling via AT1 receptors in the vasculature. However, evidence for a role of these kinases in changes of Ang II-induced vasoconstriction in obesity is still lacking. Here we sought to determine whether vascular MAPKs are differentially activated by Ang II in obese animals. The role of AT2 receptors was also evaluated. Male monosodium glutamate-induced obese (obese) and non-obese Wistar rats (control) were used. The circulating concentrations of Ang I and Ang II, determined by HPLC, were increased in obese rats. Ang II-induced isometric contraction was decreased in endothelium-intact resistance mesenteric arteries from obese compared with control rats and exhibited a retarded AT1 receptor antagonist response. Blocking of AT2 receptors and inhibition of either endothelial nitric oxide synthase (eNOS) or extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) restored Ang II-induced contraction in obese rats. Western blot analysis revealed increased protein expression of AT2 receptors in arteries from obese rats. Basal and Ang II-induced ERK1/2 phosphorylation was also increased in obese rats. Blockade of either AT1 or AT2 receptors corrected the increased ERK1/2 phosphorylation in arteries from obese rats to levels observed in control preparations. Phosphorylation of eNOS was increased in obese rats. Incubation with the ERK1/2 inhibitor before Ang II stimulation did not affect eNOS phosphorylation in control rats; however, it corrected the increased phosphorylation of eNOS in obese rats. These results clearly demonstrate that enhanced AT2 receptor and ERK1/2-induced, NO-mediated vasodilation reduces Ang II-induced contraction in an endothelium-dependent manner in obese rats.

Thyroid hormone interacts with the sympathetic nervous system to modulate bone mass and structure in young adult mice

To investigate whether thyroid hormone (TH) interacts with the sympathetic nervous system (SNS) to modulate bone mass and structure, we studied the effects of daily T3 treatment in a supraphysiological dose for 12 wk on the bone of young adult mice with chronic sympathetic hyperactivity owing to double-gene disruption of adrenoceptors that negatively regulate norepinephrine release, α(2A)-AR, and α(2C)-AR (α(2A/2C)-AR(-/-) mice). As expected, T3 treatment caused a generalized decrease in the areal bone mineral density (aBMD) of WT mice (determined by DEXA), followed by deleterious effects on the trabecular and cortical bone microstructural parameters (determined by μCT) of the femur and vertebra and on the biomechanical properties (maximum load, ultimate load, and stiffness) of the femur. Surprisingly, α(2A/2C)-AR(-/-) mice were resistant to most of these T3-induced negative effects. Interestingly, the mRNA expression of osteoprotegerin, a protein that limits osteoclast activity, was upregulated and downregulated by T3 in the bone of α(2A/2C)-AR(-/-) and WT mice, respectively. β1-AR mRNA expression and IGF-I serum levels, which exert bone anabolic effects, were increased by T3 treatment only in α(2A/2C)-AR(-/-) mice. As expected, T3 inhibited the cell growth of calvaria-derived osteoblasts isolated from WT mice, but this effect was abolished or reverted in cells isolated from KO mice. Collectively, these findings support the hypothesis of a TH-SNS interaction to control bone mass and structure of young adult mice and suggests that this interaction may involve α2-AR signaling. Finally, the present findings offer new insights into the mechanisms through which TH regulates bone mass, structure, and physiology.

Cardiac-specific suppression of NF-κB signaling prevents diabetic cardiomyopathy via inhibition of the renin-angiotensin system

Activation of NF-κB signaling in the heart may be protective or deleterious depending on the pathological context. In diabetes, the role of NF-κB in cardiac dysfunction has been investigated using pharmacological approaches that have a limitation of being nonspecific. Furthermore, the specific cellular pathways by which NF-κB modulates heart function in diabetes have not been identified. To address these questions, we used a transgenic mouse line expressing mutated IκB-α in the heart (3M mice), which prevented activation of canonical NF-κB signaling. Diabetes was developed by streptozotocin injections in wild-type (WT) and 3M mice. Diabetic WT mice developed systolic and diastolic cardiac dysfunction by the 12th week, as measured by echocardiography. In contrast, cardiac function was preserved in 3M mice up to 24 wk of diabetes. Diabetes induced an elevation in cardiac oxidative stress in diabetic WT mice but not 3M mice compared with nondiabetic control mice. In diabetic WT mice, an increase in the phospholamban/sarco(endo)plasmic reticulum Ca(2+)-ATPase 2 ratio and decrease in ryanodine receptor expression were observed, whereas diabetic 3M mice showed an opposite effect on these parameters of Ca(2+) handling. Significantly, renin-angiotensin system activity was suppressed in diabetic 3M mice compared with an increase in WT animals. In conclusion, these results demonstrate that inhibition of NF-κB signaling in the heart prevents diabetes-induced cardiac dysfunction through preserved Ca(2+) handling and inhibition of the cardiac renin-angiotensin system.

Lack of β2 -adrenoceptors aggravates heart failure-induced skeletal muscle myopathy in mice

Skeletal myopathy is a hallmark of heart failure (HF) and has been associated with a poor prognosis. HF and other chronic degenerative diseases share a common feature of a stressed system: sympathetic hyperactivity. Although beneficial acutely, chronic sympathetic hyperactivity is one of the main triggers of skeletal myopathy in HF. Considering that β2 -adrenoceptors mediate the activity of sympathetic nervous system in skeletal muscle, we presently evaluated the contribution of β2 -adrenoceptors for the morphofunctional alterations in skeletal muscle and also for exercise intolerance induced by HF. Male WT and β2 -adrenoceptor knockout mice on a FVB genetic background (β2 KO) were submitted to myocardial infarction (MI) or SHAM surgery. Ninety days after MI both WT and β2 KO mice presented to cardiac dysfunction and remodelling accompanied by significantly increased norepinephrine and epinephrine plasma levels, exercise intolerance, changes towards more glycolytic fibres and vascular rarefaction in plantaris muscle. However, β2 KO MI mice displayed more pronounced exercise intolerance and skeletal myopathy when compared to WT MI mice. Skeletal muscle atrophy of infarcted β2 KO mice was paralleled by reduced levels of phosphorylated Akt at Ser 473 while increased levels of proteins related with the ubiquitin--proteasome system, and increased 26S proteasome activity. Taken together, our results suggest that lack of β2 -adrenoceptors worsen and/or anticipate the skeletal myopathy observed in HF.

Sildenafil ameliorates oxidative stress and DNA damage in the stenotic kidneys in mice with renovascular hypertension

Background

Oxidative stress and DNA damage have been implicated in the pathogenesis of renovascular hypertension induced by renal artery stenosis in the two-kidney, one-clip (2K1C) Goldblatt model. Considering our previous report indicating that the chronic blockade of phosphodiesterase 5 with sildenafil (Viagra®) has marked beneficial effects on oxidative stress and DNA damage, we tested the hypothesis that sildenafil could also protect the stenotic kidneys of 2K1C hypertensive mice against oxidative stress and genotoxicity.

Methods

The experiments were performed with C57BL6 mice subjected to renovascular hypertension by left renal artery clipping. Two weeks after clipping, the mice were treated with sildenafil (40 mg/kg/day for 2 weeks, 2K1C-sildenafil group) or the vehicle (2K1C). These mice were compared with control mice not subjected to renal artery clipping (Sham). After hemodynamic measurements, the stenotic kidneys were assessed using flow cytometry to evaluate cell viability and the comet assay to evaluate DNA damage. Measurements of intracellular superoxide anions and hydrogen peroxide levels as well as nitric oxide bioavailability were also obtained.

Results

Sildenafil treatment significantly reduced mean arterial pressure (15%), heart rate (8%), intrarenal angiotensin II (50%) and renal atrophy (36%). In addition, it caused a remarkable decrease of reactive oxygen species production. On the other hand, sildenafil increased nitric oxide levels relative to those in the nontreated 2K1C mice. Sildenafil treatment also significantly reduced the high level of kidney DNA damage that is a characteristic of renovascular hypertensive mice.

Conclusions

Our data reveal that sildenafil has a protective effect on the stenotic kidneys of 2K1C mice, suggesting a new use of phosphodiesterase 5 inhibitors for protection against the DNA damage observed in the hypoperfused kidneys of individuals with renovascular hypertension. Further translational research is necessary to delineate the mechanisms involved in the prevention of renal stenosis in the clinical setting.

Abstract 233: Resistance Training Attenuates Renal Dysfunction in Animal Diabetic Nephropathy but Does Not Restore Kidney ACE/ACE2 Balance

Overactivity of the intrarenal renin-angiotensin system (RAS) has been implicated in the pathogenesis of diabetic nephropathy. Our group has already demonstrated that aerobic exercise reduces kidney angiotensin II levels and attenuates renal dysfunction under concurrence of diabetes and hypertension. Resistance training (RT) has recently been recognized as a useful therapeutic tool for the treatment chronic diseases and similar to aerobic exercise, has been reported to improve glycemic control. Therefore, the aim of this study was to evaluate the effect of RT on renal function and RAS in diabetic animals, to understand whether this type of exercise is also associated with renoprotection. Wistar rats (3 months old) were randomized into: sedentary control (SC); trained control (TC); sedentary diabetic (SD) and trained diabetic (TD). Animals were made diabetic with a single tail injection of streptozotocin (STZ, 50 mg/Kg). RT was performed on an 110-cm ladder (8 ladder climbs, once/day, 5 days/week, 8 weeks), carrying a load of 50-80% body weight (BW) appended to the tail. At week 8, 24 hr urine volume and albuminuria were evaluated. Kidney was excised and ACE and ACE2 activities were determined (ZPhe-HL and 7-Mca-APK(Dnp), respectively) (Two way ANOVA + Tukey test; P<0.05). RT significantly reduced blood glucose (TD = 449 ± 17 vs. SD = 572 ± 18 mg/dL) and attenuated BW loss of diabetic animals. DM reduced renal ACE activity in sedentary and trained groups (SD = 3.72 ± 0.48, TD = 3.85 ± 0.40 vs. SC = 9.2 ± 0.59 nmol/min/mg), while RT reduced enzyme activity only in control group (TC = 5.14 ± 0.26 vs. SC = 9.2 ± 0.59 nmol/min/mg). RT reduced renal ACE2 in the control group compared to the others (TC = 0.05 ± 0.0001 vs. SC = 0.09 ± 0.004, SD = 0.09 ± 0.003, TD = 0.10 ± 0.002 μM/min/mg), with no effect of diabetes on enzyme activity. RT improved renal function, decreasing urinary volume and albuminuria (DT = 4.13 ± 0.84 vs. SD = 11 ± 2.11 mg/24h) in DT group. The results from the present study show that RT is strongly associated with renoprotection in an experimental model of diabetic nephropathy. Moreover, results show that this improvement on renal function is modulated by other pathways apart from ACE and ACE2 converting enzymes. Financial Support: FAPESP, CAPES, CNPq.

Abstract 194: Low Levels of Angiotensin Converting Enzyme (ace) Do Not Prevent From Metabolic Alterations And Endothelial Dysfunction of Resistance Arteries Induced by High Fructose Intake

Purpose: ACE gene polymorphism may be associated with different responses to cardiovascular and metabolic disturbances. Therefore, we tested whether mice with low vs. normal levels of circulating and tissue ACE differently responds to chronic and excessive fructose (F) consumption.

Methods: Male mice (22±1g) harboring 1 or 2 copies of the ACE gene received F (100mg/l) or tap water for 8 weeks. Blood pressure (BP) was measured by plethysmography. Glycemia, lipids and glucose tolerance (0 to 120 min after glucose load=1.5 g/Kg ip) were also evaluated. After euthanasia, the white adipose tissue was weighed and the mesenteric resistance artery (MRA) was dissected out. Relaxation of MRA rings was evaluated in an isometric myograph in response to acetylcholine (Ach;0.01nM-30μM) or sodium nitroprusside (SNP; 0.01nM-300μM) after pre-constriction with noradrenaline.

Results: Caloric intake (~ 12.7 kcal/day) and body weight gain (1 copy: ~40%; 2 copies: ~30%) were similar among all groups. However, adipose tissue deposition was 43% higher in 1-copy F-fed mice and 36% higher in 2-copy F-fed mice in relation to the controls (p<0.05), with no influence of ACE gene copy number. F consumption increased systolic BP in 2-copy mice (1 copy: 114±2 vs. F=116±2; 2 copies: 113±2 vs. F=122±1 mmHg) while diastolic BP was increased in both F-fed groups (1 copy: 79±1 vs. F= 88±2; 2 copies: 81±2 vs. F=93±2 mmHg). This augment in BP was significantly higher in 2-copy than in 1-copy mice (p<0.05). F-fed mice also presented hyperglycemia (1 copy: 84±3 vs. F=128±5; 2 copies: 85±4 vs. F=133±8 mg/dl) as well as glucose intolerance (increase of ~67% in the area under time course curve); with no alterations in total cholesterol nor triglycerides. MRA % of relaxation was unaltered in response to SNP, while F-fed groups showed reduced relaxation response to Ach (1 copy: 87% vs. F=51%; 2 copies: 92% vs. F=57%).

Conclusions: F intake provokes glucose intolerance, increases visceral adipose tissue deposition and decreases endothelium-dependent relaxation of resistance arteries at a similar magnitude for both, 1- and 2-copy ACE gene mice, while F-induced BP increase seems to be more dependent on ACE gene dosage.

Abstract 229: Increased Ace Gene Dosage Reduces Ace2 Activity in Diabetic Mice Kidney: Involvement of Ace/ace2 Balance on the Development of Diabetic Nephropathy

The mechanisms underlying the link between high constitutive levels of ACE and diabetic nephropathy has not been completely understood, but an imbalance between angiotensin I (ACE) and II (ACE2) converting enzymes homeostasis has been described in diabetic kidney disease. The aim of this study was to evaluate ACE/ACE2 homeostasis in kidney from diabetic mice presenting increased dosage of ACE gene. Male mice (3 months old) genetically engineered to harbor one or three copies of the ACE gene were made diabetic (streptozotocin - STZ, 50 mg/Kg) and randomly assigned into: 1-copy control (1CC), 1-copy diabetic (1CD), 3-copy control (3CC) and 3-copy diabetic. At the end of experimental period body weight was evaluated and kidney was excised. Kidney-to-body weight ratio and ACE and ACE 2 activities were determined using specific substrates (ZPhe-HL and 7-Mca-APK(Dnp), respectively) (Two way ANOVA + Tukey test; P<0.05). Diabetes increased blood glucose (1CD : 436 ± 25 vs. 1CC: 90 ± 2; 3CD: 556 ± 6 vs. 3CC: 112 ± 4 mg/dL) and kidney-to-body weight ratio (1CD: 7.5 ± 0.2 vs. 1CC: 5.8 ± 0.2; 3CD: 7.8 ± 0.1 vs. 3CC: 5.8 ± 0.1 mg/g) with no influence of ACE genotype. As expected, renal ACE activity was directly related to ACE gene copy number in control group (3CC: 9.4 ± 2.11 vs. 1CC:5.6 ± 0.9 mU/mg protein). Renal ACE activity was decreased in diabetic groups (1CD: 3.6 ± 0.2 vs. 1CC: 5.6 ± 0.9; 3CD: 2.3 ± 0.4 vs. 3CC: 9.4 ± 2.1 mU/mg protein) with no influence of ACE genotype. Under physiological condition, renal ACE2 activity remained unchanged regardless of the ACE genotype (1CC: 1.9 ± 0.2 = 3CC: 1.4 ± 0.1 μM/min/mg). However upon a pathological stimulus, renal ACE2 activity was efficiently increased only in 1CD group, but not in 3CD, as compared with the others (1CD: 5.1 ± 0.9 vs. 1CC: 1.9 ± 0.2 = 3CC: 1.4 ± 0.1 = 3CD: 2.2 ± 0.2 μM/min/mg). Taken together, our results show for the first time, that susceptibility for the development of diabetic nephropathy associated with increased ACE gene dosage may be, at least in part, caused by a decrease on renal ACE2 activity. This may result in increased local levels of angiotensin II and decreased angiotensin (1-7), leading to altered glomerular permeability and albuminuria, functional alterations presented by 3CD animals. Financial Support: FAPESP, CAPES, CNPq.