202: The role of oxidative stress in developmental programming of the adult vascular phenotype

The hypercalciuria and hypermagnesuria that accompany aldosteronism contribute to a fall in plasma ionized extracellular Ca2+ and Mg2+ concentrations ([Ca2+]o and [Mg2+]o). Despite these losses and the decline in extracellular levels of these cations, total intracellular and cytosolic free Ca2+ concentration ([Ca2+]i) is increased and oxidative stress is induced. This involves diverse tissues, including peripheral blood mononuclear cells (PBMC) and plasma. The accompanying elevation in plasma parathyroid hormone (PTH) and reduction in bone mineral density caused by aldosterone (Aldo)-1% NaCl treatment (AldoST) led us to hypothesize that Ca2+ loading and altered redox state are due to secondary hyperparathyroidism (SHPT). Therefore, we studied the effects of total parathyroidectomy (PTx). In rats receiving AldoST, without or with a Ca2+-supplemented diet and/or PTx, we monitored urinary Ca2+ and Mg2+ excretion; plasma [Ca2+]o, [Mg2+]o, and PTH; PBMC [Ca2+]i and H2O2 production; plasma α1-antiproteinase activity; total Ca2+ and Mg2+ in bone, myocardium, and rectus femoris; and gp91phox labeling in the heart. We found that 1) the hypercalciuria and hypermagnesuria and decline ( P < 0.05) in plasma [Ca2+]o and [Mg2+]o that occur with AldoST were not altered by the Ca2+-supplemented diet alone or with PTx; 2) the rise ( P < 0.05) in plasma PTH with AldoST, with or without the Ca2+-supplemented diet, was prevented by PTx; 3) increased ( P < 0.05) PBMC [Ca2+]i and H2O2 production, increased total Ca2+ in heart and skeletal muscle, and fall in bone Ca2+ and Mg2+ and plasma α1-antiproteinase activity with AldoST were abrogated ( P < 0.05) by PTx; and 4) gp91phox activation in right and left ventricles at 4 wk of AldoST was attenuated by PTx. AldoST is accompanied by SHPT, with parathyroid gland-derived calcitropic hormones being responsible for Ca2+ overload in diverse tissues and induction of oxidative stress. SHPT plays a permissive role in the proinflammatory vascular phenotype.

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Abstract 311: Early Losartan Treatment Prevents the Developmental Programming of Cardiac Dysfunction Caused by Neonatal High Oxygen Exposure in Rats

Hypertension ◽

10.1161/hyp.64.suppl_1.311 ◽

2014 ◽

Vol 64 (suppl_1) ◽

Author(s):

Mariane Bertagnolli ◽

Sarah Béland-Bonenfant ◽

Anne Dios ◽

Daniela R Dartora ◽

Marie-Amélie Lukaszewski ◽

...

Keyword(s):

Oxidative Stress ◽

Cardiac Dysfunction ◽

Systolic Function ◽

Developmental Programming ◽

Term Treatment ◽

Short Term ◽

Short Term Treatment ◽

High O2 ◽

Cardiac Alterations

Neonatal oxidative stress is a major postnatal deleterious factor predisposing preterm born infants to classical complications of prematurity (retinopathy, bronchopulmonary dysplasia) which are characterized by impaired vascular development. Our group has previously shown that rats transiently exposed to high O2 as newborns (mimicking human preterms oxidative stress conditions) develop high blood pressure (BP), cardiac remodeling and dysfunction later in life, in part mediated by the renin angiotensin system (RAS). Cardiac RAS activation is characterized by AT1/AT2 receptors imbalance, with increased AT1R at adult age. In order to study the role of RAS at early stages of the developmental programming of cardiac dysfunction caused by high O2 exposure, we assessed whether an early and short-term treatment with AT1R blocker Losartan, prevents cardiac alterations at young male 4 wks-old rats (prior to the elevation of BP in this model). Sprague-Dawley newborns rats were kept with their mother in 80% O2 (O2 group, n=9) or room air (Ctrl, n=9) from days 3-10 of life (P3-P10). Losartan (LOS, n=10, 20 mg/Kg) or water was administered by gavage in O2 rats from P8-P10 (last 2 days of O2 to avoid impact on nephrogenesis). At 4 wks, echocardiography reveals that O2 rats have decreased fraction of shortening compared to Ctrl (FS: 37±2 vs 42±2 %), suggesting impaired systolic function in O2. Cardiac hypertrophy evaluated by heart/body weight and cardiomyocyte surface area (CSA) is also increased in O2 vs Ctrl (141±13 vs 118±4 μm2). LOS treatment prevented the impairment of systolic function in O2 by ameliorating FS (43±2 %) and reducing CSA (121±11 μm2). LOS treatment also modulated RAS genes expression (RT-PCR): LOS restored AT1/AT2 balance in O2 hearts by decreasing AT1b subunit (0.8±0.2 O2 vs 1.3±0.3 O2+LOS vs 0.9±0.2 Ctrl) as well as increasing ACE2 (1.5±0.4 O2 vs 0.8±0.1 O2+LOS vs 1.1±0.4 Ctrl) expressions. In conclusion, a short-term treatment with LOS during neonatal O2 exposure prevents the impairment of cardiac systolic function and hypertrophy at young age. This data reinforces the key role of RAS in the developmental programming of cardiac dysfunction and reveals LOS as an effective strategy to prevent early cardiac alterations caused by neonatal high O2 exposure.

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Abstract 135: Obesity Accelerates the Deterioration of Renal Function in Developmental Programming of Hypertension. Role of Angiotensin Ii and Oxidative Stress

Hypertension ◽

10.1161/hyp.68.suppl_1.135 ◽

2016 ◽

Vol 68 (suppl_1) ◽

Author(s):

Antonio Tapia ◽

Juan M Moreno ◽

Maria T Llinas ◽

F. Javier Salazar

Keyword(s):

Oxidative Stress ◽

Renal Function ◽

Angiotensin Ii ◽

Perinatal Period ◽

Developmental Programming ◽

Ang Ii ◽

Obese Rats ◽

Renal Vascular ◽

And Oxidative Stress

Numerous studies have shown gender-dependent differences in the deterioration of renal function in models of developmental programming of hypertension (DPH). It is also known that obesity is associated to changes in renal function and that both angiotensin II (Ang II) and oxidative stress are involved in the renal alterations that occur in obesity and in animals with DPH. The main objectives were to examine whether the increment of arterial pressure (AP) and the deterioration of renal function are accelerated as a consequence of obesity in SD rats with DPH; whether these changes are gender-dependent; and to evaluate the role of Ang II and oxidative stress in these AP and renal function changes. A high fat diet (60%) was given during the first 4 months of age and DPH was induced by an AT receptor antagonist during nephrogenic period (ARAnp). Systolic AP (mmHg) was greater (P<0.05) in ARAnp-obese rats (167 ± 3 in ♂; 146 ± 4 in ♀) than in ARAnp (155 ± 3 in ♂; 137 ± 3 in ♀); obese (147 ± 2 in ♂; 137 ± 2 in ♀) or control (127 ± 1 in ♂; 119 ± 2 in ♀) rats. Three days administration of candesartan (7 mg/kg/day) led to a decrease in AP that was greater (P<0.05) in ARAnp-obese rats (55 ± 3 in ♂; 45 ± 4 in ♀) than in ARAnp (40 ± 3 in ♂; 37 ± 4 in ♀); obese (38 ± 4 in ♂; 27 ± 4 in ♀) or control (12 ± 2 in ♂; 14 ± 3 in ♀) rats. The acute Ang II infusion (30 ng/kg/min) induced an increase in renal vascular resistance (mmHg/ml/min/gr kw) that was also greater in ARAnp-obese rats (217 ± 45% in ♂; 145 ± 38% in ♀) than in ARAnp (103 ± 9% in ♂; 97 ± 8% in ♀); obese (106 ± 14% in ♂; 106 ± 17 in ♀) or control (51 ± 7% in ♂; 51 ± 10% in ♀) rats. The response to candesartan or Ang II infusion in ARAnp-obese rats was gender-dependent and may be explained by an enhanced oxidative stress. The expression of P67phox in the renal cortex was greater (P<0.05) in ARAnp-obese rats (3,00 ± 0,05 in ♂; 2,60 ± 0,04 in ♀) than in ARAnp (1,16 ± 0,04 in ♂; 1,66 ± 0,03 in ♀); obese (0,94 ± 0,06 in ♂; 1,02 ± 0,02 in ♀) or control (1,00 ± 0,02 in ♂; 1,02 ± 0,023 in ♀) rats. The results of this study suggest that obesity at an early age enhances the hypertension and accelerates the deterioration of renal function that occurs when cardiovascular disease is programmed during the perinatal period. It is also shown that Ang II and oxidative stress seems to play an important role in these AP and renal function changes.

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