title: A gene expression analysis in rat kidney following high and low salt intake.
abstract: BACKGROUND
  The effects of salt intake on renal regulation have been investigated for decades. To find new pathways and to demonstrate the utility of oligonucleotide expression arrays, we studied whole kidneys.
  
  
  METHODS
  Eight Sprague-Dawley rats were divided into two groups. One group received a 6% salt (by weight) diet, while the other group received a 0.3%, otherwise identical, salt diet for 7 days. The rats were sacrificed after 7 days and the left kidney was subjected to RNA extraction. Oligonucleotide expression arrays (Affymetrix) were used to determine downregulation and upregulation, comparing high with low salt intake. Four rats from each group were studied separately.
  
  
  RESULTS
  The experiments were reproducible. Thirty genes were downregulated with the high-salt diet, while 35 genes were upregulated. The renin gene, beta-2 glycoprotein-1, retinol binding protein, annexin VI, and the PTP2C protein tyrosine phosphatase were among the downregulated genes. The angiotensin II receptor type 1B receptor, HMG-CoA reductase, B7 antigen, and the rat calcium channel beta subunit III were among the upregulated genes. Differentially regulated were the p55 subunit (upregulated) and the p50 subunit (downregulated) of the phosphatidyl inositol 3-kinase enzyme complex. We verified our results by selecting a high-salt downregulated gene (renin) and an upregulated gene (B7 antigen) and subjecting these genes to real-time polymerase chain reaction. The results were consistent.
  
  
  CONCLUSIONS
  Oligonucleotide expression arrays can detect novel genes encoding for proteins not generally associated with responses to varied salt intake. Experiments of this nature have substantial limitations and require detailed verification. However, overall, the utility is promising.
authors.affiliation: Max Delbrück Center for Molecular Medicine, Humboldt University of Berlin, Berlin, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Barta
authors.forename: Jan
authors.initials: J
authors.lastname: Monti
authors.forename: Philipp G
authors.initials: PG
authors.lastname: Maass
authors.forename: Kerstin
authors.initials: K
authors.lastname: Gorzelniak
authors.forename: Dominik N
authors.initials: DN
authors.lastname: Müller
authors.forename: Ralf
authors.initials: R
authors.lastname: Dechend
authors.forename: Friedrich C
authors.initials: FC
authors.lastname: Luft
authors.forename: Norbert
authors.initials: N
authors.lastname: Hübner
authors.forename: Arya M
authors.initials: AM
authors.lastname: Sharma
mesh_terms: D000818:Animals; D004039:Diet, Sodium-Restricted; D015536:Down-Regulation; D015870:Gene Expression; D066298:In Vitro Techniques; D007668:Kidney / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012083:Renin / Q000235:genetics; D015203:Reproducibility of Results; D015854:Up-Regulation
chemical_list: D012083:Renin