Effect of variations in dietary Pi intake on intestinal Pi transporters (NaPi-IIb, PiT-1, and PiT-2) and phosphate-regulating factors (PTH, FGF-23, and MEPE)

Author(s)

Aniteli, Tatiana Martins ^[1] ; de Siqueira, Flavia Ramos ^[1] ; dos Reis, Luciene Machado ^[1] ; Dominguez, Wagner Vasques ^[1] ; Costa de Oliveira, Elizabeth Maria ^[1] ; Castelucci, Patricia ^[2] ; Affonso Moyses, Rosa Maria ^[3] ; Jorgetti, Vanda ^{[1, 4]}

Affiliation

^[1] Univ Sao Paulo, Sch Med, Div Nephrol, Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Biomed Sci, Dept Anat, Sao Paulo - Brazil

^[3] Univ Nove Julho UNINOVE, Sao Paulo - Brazil

^[4] Univ Sao Paulo, Fac Med, Serv Nefrol, Ave Dr Arnaldo 455, 3 Andar, Sala 3342, BR-01246903 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY; v. 470, n. 4, p. 623-632, APR 2018.
• Web of Science Citations: 3

Abstract

Hyperphosphatemia is a common condition in patients with chronic kidney disease (CKD) and can lead to bone disease, vascular calcification, and increased risks of cardiovascular disease and mortality. Inorganic phosphate (P-i) is absorbed in the intestine, an important step in the maintenance of homeostasis. In CKD, it is not clear to what extent P-i absorption is modulated by dietary P-i. Thus, we investigated 5/6 nephrectomized (Nx) Wistar rats to test whether acute variations in dietary P-i concentration over 2 days would alter hormones involved in P-i metabolism, expression of sodium-phosphate cotransporters, apoptosis, and the expression of matrix extracellular phosphoglycoprotein (MEPE) in different segments of the small intestine. The animals were divided into groups receiving different levels of dietary phosphate: low (Nx/LPi), normal (Nx/NPi), and high (Nx/HPi). Serum phosphate, fractional excretion of phosphate, intact serum fibroblast growth factor 23 (FGF-23), and parathyroid hormone (PTH) were significantly higher and ionized calcium was significantly lower in the Nx/HPi group than in the Nx/LPi group. The expression levels of NaPi-IIb and PiT-1/2 were increased in the total jejunum mucosa of the Nx/LPi group compared with the Nx/HPi group. Modification of P-i concentration in the diet affected the apoptosis of enterocytes, particularly with P-i overload. MEPE expression was higher in the Nx/HPi group than in the Nx/NPi. These data reveal the importance of early control of P-i in uremia to prevent an increase in serum PTH and FGF-23. Uremia may be a determining factor that explains the expressional modulation of the cotransporters in the small intestine segments. (AU)

• FAPESP's process: 11/00036-0 - Study co-transporters NaP-IIb in intestinal absorption of phosphorus in uremic rats
• Grantee: Vanda Jorgetti
• Support Opportunities: Regular Research Grants