We investigated the mechanisms by which chronic administration of a multideficient diet after weaning alters bodily Na+ handling, and culminates in high systolic blood pressure (SBP) at a juvenile age. From 28 to 92 days of age, weaned male Wistar rats were given a diet with low content and poor-quality protein, and low lipid, without vitamin supplementation, which mimics the diets consumed in impoverished regions worldwide. We measured food, energy and Na+ ingestion, together with urinary Na+ excretion, Na+ density (Na+ intake/energy intake), plasma Na+ concentration, SBP, and renal proximal tubule Na+-transporting ATPases. Undernourished rats aged 92 days had only one-third of the control body mass, lower plasma albumin, higher SBP, higher energy intake, and higher positive Na+ balance accompanied by decreased plasma Na+ concentration. Losartan or Ang-(3-4) normalized SBP, and the combination of the 2 substances induced an accentuated negative Na+ balance as a result of strong inhibition of Na+ ingestion. Na+ density in undernourished rats was higher than in control, irrespective of the treatment, and they had downregulated (Na++K+)ATPase and upregulated Na+-ATPase in proximal tubule cells, which returned to control levels after Losartan or Ang-(3-4). We conclude that Na+ density, not only Na+ ingestion, plays a central role in the pathophysiology of elevated SBP in chronically undernourished rats. The observations that Losartan and Ang-(3-4) normalized SBP together with negative Na+ balance give support to the proposal that Ang II⇒AT1R and Ang II⇒AT2R axes have opposite roles within the renin-angiotensin-aldosterone system of undernourished juvenile rats.

Overweight/obesity is a growing pandemic that affects many organs and tissues. We have investigated whether a high-lipid diet provokes an imbalance between type 1 and type 2 angiotensin II (Ang II) receptors signaling, leading to liver alterations associated with cardiovascular and kidney disturbances. Chronic administration of a high-lipid diet can provoke hepatocardiorenal syndrome resulting from activation of the Ang II→type 1 receptor axis, which is entirely counteracted by Ang-(3-4), the allosteric enhancer of the Ang II→type 2 receptor pathway.

Hypertension, one of the most common and severe comorbidities of obesity and overweight, is a worldwide epidemic affecting over 30% of the population. We induced overweight in young male rats (aged 58 days) by exposure to a hypercaloric high lipid (HL) diet in which 70% of the calories originated from fat. The HL diet also contained 33 or 57% higher Na+ than the control (CTR) diet. Over the following weeks the HL rats gradually became overweight (490 ± 12 g vs 427 ± 7 g in the CTR group after 15 weeks) with high visceral fat. They developed elevated systolic blood pressure (SBP) (141 ± 1.9 mmHg), which was fully restored to CTR values (128 ± 1.1 mmHg) by oral administration of Ang-(3-4) (Val-Tyr), the shortest renin-angiotensin-derived peptide. The overweight rats had lower plasma Na+ concentration that augmented to CTR values by Ang-(3-4) treatment. Na+ ingestion was depressed by 40% as result of the Ang-(3-4) treatment, whereas the urinary excretion of Na+ (UNaV) remained unmodified. The preservation of UNaV after Ang-(3-4) treatment - despite the sharp decrease in the dietary Na+ intake - can be ascribed to the normalization of renal type 1 angiotensin II receptors and Na+-transporting ATPases, both up-regulated in overweight rats. These renal effects complete a counterregulatory action on elevated renin-angiotensin activity that allows the high SBP to be normalized and body Na+ homeostasis to be restored concomitantly in overweight rats.

α-Tocopherol (α-Toc) overload increases the risk of dying in humans (E.R. Miller III et al. Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality Ann Int Med. 142 (2005) 37-46), and overload during early development leads to elevation of blood pressure at adult life, but the mechanism(s) remains unknown. We hypothesized that α-Toc overload during organogenesis affects the renal renin angiotensin system (RAS) components and renal Na+ handling, culminating with late elevated blood pressure. Pregnant Wistar rats received α-Toc or the superoxide dismutase mimetic tempol throughout pregnancy. We evaluated components of the intrarenal renin angiotensin system in neonate and juvenile offspring: Ang II-positive cells, Ang II receptors (AT1 and AT2), linked protein kinases, O2- production, NADPH oxidase abundance, lipid peroxidation and activity of Na+-transporting ATPases. In juvenile offspring we followed the evolution of arterial blood pressure. Neonates from α-Toc and tempol mothers presented with accentuated retardment in tubular development, pronounced decrease in glomerular Ang II-positive cells and AT1/AT2 ratio, intense production of O2- and upregulation of the α, ε and λ PKC isoforms. α-Toc decreased or augmented the abundance of renal (Na++K+)ATPase depending on the age and α-Toc dose. In juvenile rats the number of Ang II-positive cells returned to control values as well as PKCα, but co-existing with marked upregulation in the activity of (Na++K+) and Na+-ATPase and elevated arterial pressure at 30 days. We conclude that the mechanisms of these alterations rely on selective targeting of renal RAS components through genic and pro-oxidant effects of the vitamin.