Fernanda Barrinha Fernandes

Aerobic Exercise Training–Induced Left Ventricular Hypertrophy Involves Regulatory MicroRNAs, Decreased Angiotensin-Converting Enzyme-Angiotensin II, and Synergistic Regulation of Angiotensin-Converting Enzyme 2-Angiotensin (1-7)

Aerobic exercise training leads to a physiological, nonpathological left ventricular hypertrophy; however, the underlying biochemical and molecular mechanisms of physiological left ventricular hypertrophy are unknown. The role of microRNAs regulating the classic and the novel cardiac renin-angiotensin (Ang) system was studied in trained rats assigned to 3 groups: (1) sedentary; (2) swimming trained with protocol 1 (T1, moderate-volume training); and (3) protocol 2 (T2, high-volume training). Cardiac Ang I levels, Ang-converting enzyme (ACE) activity, and protein expression, as well as Ang II levels, were lower in T1 and T2; however, Ang II type 1 receptor mRNA levels (69% in T1 and 99% in T2) and protein expression (240% in T1 and 300% in T2) increased after training. Ang II type 2 receptor mRNA levels (220%) and protein expression (332%) were shown to be increased in T2. In addition, T1 and T2 were shown to increase ACE2 activity and protein expression and Ang (1-7) levels in the heart. Exercise increased microRNA-27a and 27b, targeting ACE and decreasing microRNA-143 targeting ACE2 in the heart. Left ventricular hypertrophy induced by aerobic training involves microRNA regulation and an increase in cardiac Ang II type 1 receptor without the participation of Ang II. Parallel to this, an increase in ACE2, Ang (1-7), and Ang II type 2 receptor in the heart by exercise suggests that this nonclassic cardiac renin-angiotensin system counteracts the classic cardiac renin-angiotensin system. These findings are consistent with a model in which exercise may induce left ventricular hypertrophy, at least in part, altering the expression of specific microRNAs targeting renin-angiotensin system genes. Together these effects might provide the additional aerobic capacity required by the exercised heart.

Reciprocal changes in renal ACE/ANG II and ACE2/ANG 1–7 are associated with enhanced collecting duct renin in Goldblatt hypertensive rats

Alterations in the balance between ANG II/ACE and ANG 1-7/ACE2 in ANG II-dependent hypertension could reduce the generation of ANG 1-7 and contribute further to increased intrarenal ANG II. Upregulation of collecting duct (CD) renin may lead to increased ANG II formation during ANG II-dependent hypertension, thus contributing to this imbalance. We measured ANG I, ANG II, and ANG 1-7 contents, angiotensin-converting enzyme (ACE) and ACE2 gene expression, and renin activity in the renal cortex and medulla in the clipped kidneys (CK) and nonclipped kidneys (NCK) of 2K1C rats. After 3 wk of unilateral renal clipping, systolic blood pressure and plasma renin activity increased in 2K1C rats (n = 11) compared with sham rats (n = 9). Renal medullary angiotensin peptide levels were increased in 2K1C rats [ANG I: (CK = 171 ± 4; NCK = 251 ± 8 vs. sham = 55 ± 3 pg/g protein; P < 0.05); ANG II: (CK = 558 ± 79; NCK = 328 ± 18 vs. sham = 94 ± 7 pg/g protein; P < 0.001)]; and ANG 1-7 levels decreased (CK = 18 ± 2; NCK = 19 ± 2 pg/g vs. sham = 63 ± 10 pg/g; P < 0.001). In renal medullas of both kidneys of 2K1C rats, ACE mRNA levels and activity increased but ACE2 decreased. In further studies, we compared renal ACE and ACE2 mRNA levels and their activities from chronic ANG II-infused (n = 6) and sham-operated rats (n = 5). Although the ACE mRNA levels did not differ between ANG II rats and sham rats, the ANG II rats exhibited greater ACE activity and reduced ACE2 mRNA levels and activity. Renal medullary renin activity was similar in the CK and NCK of 2K1C rats but higher compared with sham. Thus, the differential regulation of ACE and ACE2 along with the upregulation of CD renin in both the CK and NCK in 2K1C hypertensive rats indicates that they are independent of perfusion pressure and contribute to the altered content of intrarenal ANG II and ANG 1-7.

Effects of Exercise Training on Circulating and Skeletal Muscle Renin-Angiotensin System in Chronic Heart Failure Rats

Background Accumulated evidence shows that the ACE-AngII-AT1 axis of the renin-angiotensin system (RAS) is markedly activated in chronic heart failure (CHF). Recent studies provide information that Angiotensin (Ang)-(1–7), a metabolite of AngII, counteracts the effects of AngII. However, this balance between AngII and Ang-(1–7) is still little understood in CHF. We investigated the effects of exercise training on circulating and skeletal muscle RAS in the ischemic model of CHF. Methods/Main Results Male Wistar rats underwent left coronary artery ligation or a Sham operation. They were divided into four groups: 1) Sedentary Sham (Sham-S), 2) exercise-trained Sham (Sham-Ex), sedentary CHF (CHF-S), and exercise-trained CHF (CHF-Ex). Angiotensin concentrations and ACE and ACE2 activity in the circulation and skeletal muscle (soleus and plantaris) were quantified. Skeletal muscle ACE and ACE2 protein expression, and AT1, AT2, and Mas receptor gene expression were also evaluated. CHF reduced ACE2 serum activity. Exercise training restored ACE2 and reduced ACE activity in CHF. Exercise training reduced plasma AngII concentration in both Sham and CHF rats and increased the Ang-(1–7)/AngII ratio in CHF rats. CHF and exercise training did not change skeletal muscle ACE and ACE2 activity and protein expression. CHF increased AngII levels in both soleus and plantaris muscle, and exercise training normalized them. Exercise training increased Ang-(1–7) in the plantaris muscle of CHF rats. The AT1 receptor was only increased in the soleus muscle of CHF rats, and exercise training normalized it. Exercise training increased the expression of the Mas receptor in the soleus muscle of both exercise-trained groups, and normalized it in plantaris muscle. Conclusions Exercise training causes a shift in RAS towards the Ang-(1–7)-Mas axis in skeletal muscle, which can be influenced by skeletal muscle metabolic characteristics. The changes in RAS circulation do not necessarily reflect the changes occurring in the RAS of skeletal muscle.

Tacrolimus pharmacokinetic drug interactions: effect of prednisone, mycophenolic acid or sirolimus

This study was conducted to evaluate time‐dependent pharmacokinetic changes and drug interactions over the first 6 months after transplantation in kidney transplant recipients receiving tacrolimus (TAC), prednisone (PRED) and mycophenolate mofetil (MMF) or sirolimus (SRL). Pharmacokinetic assessments were carried out at day 7 and months 1, 3, and 6 in kidney transplant recipients receiving TAC plus PRED with either MMF (2 g/day, n = 13) or SRL (15 mg loading dose, 5 mg for 7 days followed by 2 mg/day, n = 12). There were no differences in the main demographic characteristics or in mean PRED doses during the first 6 months after transplant. From day 7 to month 6, there was a 65% increase in TAC dose corrected exposure (dose corrected area under the curve; AUC) in patients receiving MMF (P = 0.005) and a 59% increase in TAC dose corrected exposure in patients receiving SRL (P = 0.008). From day 7 to month 6, there was a 72% increase in mycophenolate dose corrected exposure (P = 0.001) and a 65% increase in SRL dose corrected exposure (P = 0.008). TAC dose corrected exposure was 23% lower in patients receiving SRL compared with MMF (P = 0.012) on average over the study period. PRED dose reduction was associated with increase in TAC (in patients receiving SRL, P = 0.040) and mycophenolic acid (MPA) (P = 0.070) drug exposures. Tercile distribution of TAC drug exposure showed a positive correlation with mean SRL exposures (P = 0.016). Conversely, tercile distribution of SRL drug exposure showed a positive correlation with mean TAC exposures (P = 0.004). Time‐dependent increases in TAC, MPA and SRL drug exposures occur up to 6 months after transplantation. Drug‐to‐drug interactions indicate that intense therapeutic drug monitoring is required to avoid under‐ or over‐immunosuppression.

Renovascular remodeling and renal injury after extended angiotensin II infusion

Chronic angiotensin II (ANG II) infusion for 1 or 2 wk leads to progressive hypertension and induces inward hypertrophic remodeling in preglomerular vessels, which is associated with increased renal vascular resistance (RVR) and decreased glomerular perfusion. Considering the ability of preglomerular vessels to exhibit adaptive responses, the present study was performed to evaluate glomerular perfusion and renal function after 6 wk of ANG II infusion. To address this study, male Wistar rats were submitted to sham surgery (control) or osmotic minipump insertion (ANG II 200 ng·kg(-1)·min(-1), 42 days). A group of animals was treated or cotreated with losartan (10 mg·kg(-1)·day(-1)), an AT1 receptor antagonist, between days 28 and 42 Chronic ANG II infusion increased systolic blood pressure to 185 ± 4 compared with 108 ± 2 mmHg in control rats. Concomitantly, ANG II-induced hypertension increased intrarenal ANG II level and consequently, preglomerular and glomerular injury. Under this condition, ANG II enhanced the total renal plasma flow (RPF), glomerular filtration rate (GFR), urine flow and induced pressure natriuresis. These changes were accompanied by lower RVR and enlargement of the lumen of interlobular arteries and afferent arterioles, consistent with impairment of renal autoregulatory capability and outward preglomerular remodeling. The glomerular injury culminated with podocyte effacement, albuminuria, tubulointerstitial macrophage infiltration and intrarenal extracellular matrix accumulation. Losartan attenuated most of the effects of ANG II. Our findings provide new information regarding the contribution of ANG II infusion over 2 wk to renal hemodynamics and function via the AT1 receptor.

N-domain isoform of Angiotensin I converting enzyme as a marker of hypertension: populational study.

The aim of this paper was to investigate the presence of the urinary 90 kDa N-domain ACE in a cohort of the population from Vitoria, Brazil, to verify its association with essential hypertension since this isoform could be a possible genetic marker of hypertension. Anthropometric, clinical, and laboratory parameters of the individuals were evaluated (n = 1150) and the blood pressure (BP) was measured. The study population was divided according to ACE isoforms in urine as follows: ACE 65/90/190, presence of three ACE isoforms (n = 795), ACE 90+ (65/90) (n = 186), and ACE 90− (65/190) (n = 169) based on the presence (+) or absence (−) of the 90 kDa ACE isoform. The anthropometric parameters, lipid profile, serum levels of uric acid, glucose, and the systolic and diastolic BP were significantly greater in the ACE 90+ compared with the ACE 90− and ACE 65/90/190 individuals. We found that 98% of individuals from the ACE 90+ group and 38% from the ACE 65/90/190 group had hypertension, compared to only 1% hypertensive individuals in the ACE 90− group. There is a high presence of the 90 kDa N-domain ACE isoform (85%) in the studied population. The percentile of normotensive subjects with three isoforms was 62%. Our findings could contribute to the development of new efficient strategy to prevent and treat hypertension to avoid the development of cardiovascular disease.

Spectroscopic and structural analysis of somatic and N-domain angiotensin I-converting enzyme isoforms from mesangial cells from Wistar and spontaneously hypertensive rats

Angiotensin I-converting enzyme (ACE) plays a key role in the renin-angiotesin aldosterone cascade. We analysed the secondary structure and structural organization of a purified 65kDa N-domain ACE (nACE) from Wistar rat mesangial cells, a 90 kDa nACE from spontaneously hypertensive rats and a 130 kDa somatic ACE. The C-terminal alignment of the 65 kDa nACE with rat ACE revealed that the former was truncated at Ser(482), and the sequence of the 90 kDa nACE ended at Pro(629). Proteins secondary structure consisted predominantly of alpha-helices. The 90 and 65 kDa isoforms were the most stable in guanidine and at low pH, respectively. Enzymatic activity decreased with loss in secondary structure, except in the case of guanidine HCl where the 90 kDa fragment loses its secondary structure faster than its enzymatic activity. We identified and characterized the activity and stability of these isoforms and these findings would be helpful on the understanding of the role of nACE isoforms in hypertension.

Association of Urinary N-Domain Angiotensin I-Converting Enzyme with Plasma Inflammatory Markers and Endothelial Function

The aim of this study was to investigate the association between urinary 90 kDa N-domain Angiotensin I-converting enzyme (ACE) form with C-reactive protein (CRP) and homocysteine plasma levels (Hcy), urinary nitric oxide (NOu), and endothelial function (EF) in normotensive subjects. Forty healthy subjects were evaluated through brachial Doppler US to test the response to reactive hyperemia and a panel of blood tests to determine CRP and Hcy levels, NOu, and urinary ACE. They were divided into groups according to the presence (ACE90+) or absence (ACE90−) of the 90 kDa ACE, the presence (FH+) or absence (FH−) of family history of hypertension, and the presence or absence of these two variables FH+/ACE90+ and FH−/ACE90−. We found an impaired endothelial dilatation in subjects who presented the 90 kDa N-domain ACE as follows: 11.4% ± 5.3% in ACE90+ compared with 17.6% ± 7.1% in ACE90− group and 12.4% ± 5.6% in FH+/ACE90+ compared with 17.7% ± 6.2% in FH−/ACE90− group, P < 0.05. Hcy and CRP levels were statistically significantly lower in FH+/ACE90+ than in FH−/ACE90− group, as follows: 10.0 ± 2.3 µM compared with 12.7 ± 1.5 µM, and 1.3 ± 1.8 mg/L compared with 3.6 ± 2.0 mg/L, respectively. A correlation between flow-mediated dilatation (FMD) and CRP, Hcy, and NOu levels was not found. Our study suggests a reduction in the basal NO production confirmed by NOu analysis in subjects with the 90 kDa N-domain ACE isoform alone or associated with a family history of hypertension. Our data suggest that the presence of the 90 kDa N-domain ACE itself may have a negative impact on flow-mediated dilatation stimulated by reactive hyperemia.

Association of urinary 90 kDa angiotensin- converting enzyme with family history of hypertension and endothelial function in normotensive individuals.

We described angiotensin-I-converting enzyme (ACE) isoforms with molecular masses of 190, 90, and 65 kDa in the urine of normotensive offspring of hypertensive subjects. Since they did not appear in equal amounts, we suggested that 90 kDa ACE might be a marker for hypertension. We evaluated the endothelial response in normotensive offspring with or without family history of hypertension and its association with the 90 kDa ACE in urine. Thirty-five normotensive subjects with a known family history of hypertension and 20 subjects without a family history of hypertension, matched for age, sex, body weight, and blood pressure, were included in the study. Endothelial function was assessed by ultrasound and a sample of urine was collected for determination of ACE isoforms. In the presence of a family history of hypertension and detection of 90 kDa ACE, we noted a maximal flow mediated dilation of 12.1 +/- 5.0 vs 16.1 +/- 6.0% in those without a previous history of hypertension and lacking urinary 90 kDa ACE (P < 0.05). In subjects with a family history of hypertension and presenting 90 kDa ACE, there were lower levels of HDL-cholesterol (P < 0.05) and higher levels of triglycerides (P < 0.05). Subjects with 90 kDa ACE irrespective of hypertensive history presented a trend for higher levels of triglycerides and HDL-cholesterol (P = 0.06) compared to subjects without 90 kDa ACE. Our data suggest that the 90 kDa ACE may be a marker for hypertension which may be related to the development of early atherosclerotic changes.

Direct renin inhibition is not enough to prevent reactive oxygen species generation and vascular dysfunction in renovascular hypertension

Abstract Renin‐angiotensin system activation promotes oxidative stress and endothelial dysfunction. However, no previous study has examined the effects of the renin inhibitor aliskiren, either alone or combined with angiotensin II type 1 antagonists on alterations induced by two‐kidney, one‐clip (2K1C) hypertension. We compared the vascular effects of aliskiren (50 mg/kg/day), losartan (10 mg/kg/day), or both by gavage for 4 weeks in 2K1C and control rats. Treatment with losartan, aliskiren, or both exerted similar antihypertensive effects. Aliskiren lowered plasma Ang I concentrations in sham rats and in hypertensive rats treated with aliskiren or with both drugs. Aliskiren alone or combined with losartan decreased plasma angiotensin II concentrations measured by high performance liquid chromatography, whereas losartan alone had no effects. In contrast, losartan alone or combined with aliskiren abolished hypertension‐induced increases in aortic angiotensin II concentrations, whereas aliskiren alone exerted no such effects. While hypertension enhanced aortic oxidative stress assessed by dihydroethidium fluorescence and by lucigenin chemiluminescence, losartan alone or combined with aliskiren, but not aliskiren alone, abolished this alteration. Hypertension impaired aortic relaxation induced by acetylcholine, and losartan alone or combined with aliskiren, but not aliskiren alone, reversed this alteration. Losartan alone or combined with aliskiren, but not aliskiren alone, increased plasma nitrite concentrations in 2K1C rats. These findings show that antihypertensive effects of aliskiren do not prevent hypertension‐induced vascular oxidative stress and endothelial dysfunction. These findings contrast those found with losartan and suggest that renin inhibition is not enough to prevent hypertension‐induced impaired redox biology and vascular dysfunction.