Diets rich in saturated fat and/or salt differentially modulate atrial natriuretic peptide and renin expression in C57BL/6 mice.

PURPOSE: To study the effects of a diet rich in salt and/or saturated fat on atrial natriuretic peptide (ANP)-granules, hypertension, renin expression, and cardiac structure in C57Bl/6 mice. METHODS: Young adult male mice were separated into four groups (n = 12) and fed one of the following for 9 weeks: standard chow/normal salt (SC-NS), high-fat chow/normal salt (HF-NS), standard chow/high salt (SC-HS) and high-fat chow/high salt (HF-HS). Alterations in the serum ANP, ultrastructural analysis of cardiomyocytes that produce ANP, structural analysis of the left ventricle, blood pressure, renin expression, glomerular filtration rate (GFR), feed efficiency, and lipid and glucose parameters were examined. RESULTS: The HF-NS diet showed a small increase in ANP production and left ventricular hypertrophy, increased food efficiency, and abnormal lipid and glucose parameters. The SC-HS diet showed a large increase in ANP granules in myocytes and corresponding elevation in ANP serum levels, left ventricular hypertrophy, hypertension, decrease in renin levels, and increase in GFR. The combination of the two diets (HF-HS) had an additive effect. CONCLUSION: The incorporation of a high-fat high-salt diet induced ultrastructural changes in cardiomyocytes, increased the production of ANP and increased its serum level, and reduced the amount of renin in the kidney.

Papel do antioxidante (vitamina C) na modulação da pressão sanguínea em ratos espontaneamente hipertensos (SHR) / The role of antioxidant (vitamin C) in the modulation of the blood pressure in spontaneously hypertensive rats (SHR)

A hipertensão essencial humana, bem como a hipertensão desenvolvida em Ratos Espontaneamente Hipertensos (SHR), são caracterizadas pelo desenvolvimento de Pressão Arterial (PA) elevada na medida em que a idade avança, sem identificação da causa primária. Está bem estabelecido que este modelo animal apresenta estresse oxidativo (EOx) concomitante a hipertensão. O mecanismo pelo qual o antioxidante reduz a pressão não está claro, por essa razão, é necessário avaliar o comportamento destas enzimas envolvidas na homeostase da PA. Ratos Wistar-Kyoto (WKY) e SHR machos receberam ácido ascórbico, 200 mg / kg / dia por sonda orogástrica durante cinco semanas. A PA, a Hipertrofia Ventricular Esquerda (HVE), o Sistema Renina-Angiotensina (SRA), o Peptídeo Natriurético Atrial (ANP) e o EOx foram comparados entre os grupos por pletismografia, estereologia, microscopia confocal de varrimento a laser, microscopia eletrônica de transmissão, western blotting e análise do RT-qPCR. Os SHR tratados com ácido ascórbico reduziram a PA e a HVE. Além disso, as enzimas envolvidas na homeostase da PA, a renina e a Enzima Conversora de Angiotensina (ECA) normalizaram-se, bem como os Receptores tipo 1 de Angiotensina II (AT1). A grande quantidade de grânulos de ANP no grupo SHR foi reduzida pelo tratamento com ácido ascórbico. O balanço oxidativo foi restabelecido nos SHR tratados com este antioxidante. O EOx nos SHR eleva os níveis de renina e de PA. Estas espécies reativas de oxigênio podem ser envolvidas no mecanismo de sinalização para aumentar a expressão de ANP nos miócitos atriais. Estes dados também mostram que o tratamento com o antioxidante (vitamin C) reduz o EOx e normaliza a PA ao menos parcialmente pela redução de taxas de renina...

The essential hypertension, as well as the Spontaneously Hypertensive Rat (SHR), is characterized by the development of high BP (BP) with advancing age, with no identified primary cause. It is well established that this animal model presents OxS concomitant hypertension. The mechanism, by which the antioxidant reduces the pressure, is not clear, for this reason, it is necessary to evaluate the behavior of enzymes involved in the homeostasis of BP. Male Wistar-Kyoto (WKY) rats and SHR received ascorbic acid, 200 mg / kg / day by orogastric gavage with lasted five weeks. The BP, Left Ventricular Hypertrophy (LVH), renin-angiotensin system (RAS), Atrial Natriuretic Peptide (ANP) and OxS results have been extensively compared among groups by plethysmography, stereology, confocal laser scanning microscopy, transmission electron microscopy, western blotting and RT-qPCR analysis. The SHR treated with ascorbic acid reduced BP and LVH. Also, the enzymes involved in the homeostasis of BP, renin and Angiotensin Converting Enzyme (ACE) normalized, as well as Angiotensin II type 1 receptor (AT1R). The large amount of ANP granules in SHR group was reduced by treatment with ascorbic acid. Oxidative balance was reestablished in SHR treated with this antioxidant. OxS in SHR elevates renin levels and BP. These reactive oxygen species may be involved in the signaling mechanism for increased expression in ANP atrial myocytes. These data also show that treatment with antioxidant (vitamin C) reduces OxS and normalizes BP at least partly by reducing rates of renin...