Chronic high-sodium diet intake after weaning lead to neurogenic hypertension in adult Wistar rats

Figures

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  Figure 1. Sodium (Na) intake (A), sodium excretion (B) and 24-hours sodium balance (C) of rats from HS, HS Unload and respective control groups. Measurements were performed on the 4th (4 W), 8th (8 W), 12th (12 W) and 15th (15 W) weeks after weaning for 24 h in metabolic cages. Scattered squares (Cont) and circles (HS/HS Unload) represent individual values and bars represent average group data. Differences between pairs of means are indicated by different letters. Same letter means no statistical difference. Two Way ANOVA followed by Bonferroni’s post-test; p < 0.05.

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  Figure 2. Baseline levels of mean arterial blood pressure (MAP) and heart rate (HR) in rats from HS, HS Unload and respective control groups. Direct measurements of MAP and HR were performed on the 12th and 15th weeks after weaning. Scattered squares (Cont) and circles (HS/HS Unload) represent individual values and bars represent average group data. Average mean ± SEM are indicated under the bottom of respective bars. Horizontal dashed lines define the boundaries for control MAP and HR range. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) for all groups are shown in the smaller panels (C through F). *Different of control group; one way ANOVA followed by Bonferroni’s post-test; **different of HS group; one way ANOVA followed by Bonferroni’s post-test; p < 0.05.

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  Figure 3. MAP and HR levels before and after hexamethonium injection in rats from HS, HS Unload and respective control groups. Experiments were carried out on the 12th (for HS group) and 15th (for HS Unload group) weeks after weaning. Vertical dashed lines indicate the moment of the i.v. injection of hexamethonium (20 mg/kg). Panels B,D,F,H represent the change in MAP and HR 7 to 11 minutes after the injection. *Different of control; two-way ANOVA for repeated measurements followed by Bonferroni’s post-test; p < 0.05. **Different of control; unpaired t-test; p < 0.05.

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  Figure 4. Cardiovascular effects of central losartan microinjection into the lateral cerebral ventricle (LCV). Direct measurements of blood pressure were performed on the 12th week after weaning in rats from HS and respective control groups. Vertical dashed line mark the losartan microinjection (180 nmol/kg) event. Panels A and B represent absolute levels of MAP and HR over time and panels C and D represent change of MAP and HR 60 minutes after injection. Panel E shows a coronal brain slice at the lateral cerebral ventricle (LCV) level with the guide cannula tract (black arrow) indicating microinjection into the LCV. *Different of Cont group; two-way ANOVA for repeated measurements followed by Bonferroni’s post-test; p < 0.05.

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  Figure 5. CSF and plasma concentration of sodium [Na+], potassium [K+], chloride [Cl−] and osmolality. Panels A and E represent [Na+] in CSF and plasma; (B and F) represent [K+] in CSF and plasma; (C and G) represent [Cl−] concentration in CSF and plasma and (D and H) represent osmolality measured in fresh samples. Measurements were performed in samples from HS and Cont rats on the 12th weeks after weaning. *Different of Cont group; unpaired t-test; p < 0.05.

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  Figure 6. Photomicrograph histological section of the kidneys and heart from rats fed with regular (Cont) or high-sodium (HS) diet. Panel A: cortical areas of the kidneys were evaluated and renal corpuscles analysed. Grey and white arrows point to the edges of the glomerular tuft (Gr) and Bowman’s capsule respectively. No inflammatory process was detected in the kidneys sections of both groups. Kidney photomicrographs were taken using 400x magnification (bar = 50 µm). Panel B: transversal cut of the hearts taken using 1x magnification (bar = 2 mm). Black arrow point to the edge of the left ventricle lumen (LVL).