Renal Effects and Underlying Molecular Mechanisms of Long-Term Salt Content Diets in Spontaneously Hypertensive Rats

PLoS One. 2015 Oct 23;10(10):e0141288. doi: 10.1371/journal.pone.0141288. eCollection 2015.

Abstract

Several evidences have shown that salt excess is an important determinant of cardiovascular and renal derangement in hypertension. The present study aimed to investigate the renal effects of chronic high or low salt intake in the context of hypertension and to elucidate the molecular mechanisms underlying such effects. To this end, newly weaned male SHR were fed with diets only differing in NaCl content: normal salt (NS: 0.3%), low salt (LS: 0.03%), and high salt diet (HS: 3%) until 7 months of age. Analysis of renal function, morphology, and evaluation of the expression of the main molecular components involved in the renal handling of albumin, including podocyte slit-diaphragm proteins and proximal tubule endocytic receptors were performed. The relationship between diets and the balance of the renal angiotensin-converting enzyme (ACE) and ACE2 enzymes was also examined. HS produced glomerular hypertrophy and decreased ACE2 and nephrin expressions, loss of morphological integrity of the podocyte processes, and increased proteinuria, characterized by loss of albumin and high molecular weight proteins. Conversely, severe hypertension was attenuated and renal dysfunction was prevented by LS since proteinuria was much lower than in the NS SHRs. This was associated with a decrease in kidney ACE/ACE2 protein and activity ratio and increased cubilin renal expression. Taken together, these results suggest that LS attenuates hypertension progression in SHRs and preserves renal function. The mechanisms partially explaining these findings include modulation of the intrarenal ACE/ACE2 balance and the increased cubilin expression. Importantly, HS worsens hypertensive kidney injury and decreases the expression nephrin, a key component of the slit diaphragm.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin-Converting Enzyme 2
  • Animals
  • Diet, Sodium-Restricted
  • Glomerular Filtration Barrier / metabolism
  • Hypertension / diet therapy*
  • Hypertension / pathology
  • Hypertension / urine
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Kidney / enzymology*
  • Kidney / pathology
  • Kidney / physiopathology
  • Male
  • Membrane Proteins / metabolism
  • Peptidyl-Dipeptidase A / metabolism
  • Rats, Inbred SHR
  • Renin-Angiotensin System
  • Sodium Chloride, Dietary / metabolism

Substances

  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • NPHS2 protein
  • Sodium Chloride, Dietary
  • nephrin
  • Peptidyl-Dipeptidase A
  • Ace2 protein, rat
  • Angiotensin-Converting Enzyme 2

Grants and funding

This study was supported by the grants from the National Council for Scientific and Technological Development, CNPq, http://lattes.cnpq.br/ (No. 302563-2011/3 and No. 400484/2013-7) to JGM, Support Foundation of São Paulo Research, FAPESP, http://www.fapesp.br/ (2012/10146-0 and 2013/10619-8) to ACCG, and Support Foundation of Minas Gerais, FAPEMIG, http://www.fapemig.br/, to RAAS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.