In:
American Journal of Nephrology, S. Karger AG, Vol. 35, No. 5 ( 2012), p. 401-408
Abstract:
〈 i 〉 Background: 〈 /i 〉 Vitamin D receptor activation with paricalcitol can modulate the transcription of renin-angiotensin system components in the surgical 5/6 nephrectomy rat model (5/6 NX) of chronic renal insufficiency. We tested the hypothesis whether dietary modification of phosphate influences kidney renin-angiotensin system gene expression at the mRNA level in 5/6 NX rats. 〈 i 〉 Methods: 〈 /i 〉 Fifteen weeks after surgery, rats were given control diet (0.3% calcium, 0.5% phosphate), phosphate-lowering diet (3% calcium as carbonate) or high-phosphate diet (1.5%) for 12 weeks. Sham-operated rats were on control diet. 〈 i 〉 Results: 〈 /i 〉 Blood pressure, plasma phosphate, parathyroid hormone, glomerulosclerosis, tubulointerstitial damage, and FGF-23 were increased in remnant kidney rats, whereas creatinine clearance was decreased. Phosphate, parathyroid hormone, glomerulosclerosis, tubulointerstitial damage, and FGF-23 were further elevated by the high-phosphate diet, but were reduced by the phosphate-lowering diet. Plasma calcium was increased with the phosphate-lowering diet and decreased with the high-phosphate diet. Remnant kidney rats on control diet showed upregulated kidney angiotensin-converting enzyme (ACE) and angiotensin (Ang) IV receptor (AT 〈 sub 〉 4 〈 /sub 〉 ) transcription, while ACE2, Ang II type 2 receptor and renin receptor transcription were downregulated in comparison with sham rats. Phosphate-lowering diet reduced whereas high-phosphate diet increased kidney ACE, and these effects were observed at both mRNA and protein levels. Dietary phosphate loading also resulted in lower AT 〈 sub 〉 1a 〈 /sub 〉 gene transcription. 〈 i 〉 Conclusion: 〈 /i 〉 Dietary phosphate loading was associated with elevated kidney ACE expression, increased tissue damage and lower AT 〈 sub 〉 1a 〈 /sub 〉 transcription in 5/6 NX rats. Phosphate binding with 3% calcium carbonate had opposite effects on ACE and kidney damage.
Type of Medium:
Online Resource
ISSN:
0250-8095
,
1421-9670
Language:
English
Publisher:
S. Karger AG
Publication Date:
2012
detail.hit.zdb_id:
1468523-1
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