Effects of Prolonged High Phosphorus Diet on Phosphorus and Calcium Balance in Rats

Yoshiko Tani; Tadatoshi Sato; Hisami Yamanaka-Okumura; Hironori Yamamoto; Hidekazu Arai; Naoki Sawada; Kaori Genjida; Yutaka Taketani; Eiji Takeda

doi:10.3164/jcbn.40.221

Original Articles

Effects of Prolonged High Phosphorus Diet on Phosphorus and Calcium Balance in Rats

Yoshiko Tani, Tadatoshi Sato, Hisami Yamanaka-Okumura, Hironori Yamamoto, Hidekazu Arai, Naoki Sawada, Kaori Genjida, Yutaka Taketani, Eiji Takeda

Author information

Yoshiko Tani
Department of Clinical Nutrition, Institute of Health Biosciences, The University of Tokushima Graduate School
Tadatoshi Sato
Department of Clinical Nutrition, Institute of Health Biosciences, The University of Tokushima Graduate School
Hisami Yamanaka-Okumura
Department of Clinical Nutrition, Institute of Health Biosciences, The University of Tokushima Graduate School
Hironori Yamamoto
Department of Clinical Nutrition, Institute of Health Biosciences, The University of Tokushima Graduate School
Hidekazu Arai
Department of Clinical Nutrition, Institute of Health Biosciences, The University of Tokushima Graduate School
Naoki Sawada
Department of Clinical Nutrition, Institute of Health Biosciences, The University of Tokushima Graduate School
Kaori Genjida
Department of Clinical Nutrition, Institute of Health Biosciences, The University of Tokushima Graduate School
Yutaka Taketani
Department of Clinical Nutrition, Institute of Health Biosciences, The University of Tokushima Graduate School
Eiji Takeda
Department of Clinical Nutrition, Institute of Health Biosciences, The University of Tokushima Graduate School

Keywords: high phosphorus diet, mature rat, phosphorus balance, parathyroid hormone (PTH), sodium-dependent phosphate transporter (Npt)

JOURNAL FREE ACCESS

2007 Volume 40 Issue 3 Pages 221-228

DOI https://doi.org/10.3164/jcbn.40.221

Details

Abstract

The amount of phosphorus contained in food as food additives is currently increasing and a high intake of phosphorus can cause various diseases. To determine the effects of a prolonged high phosphorus diet, here we investigated the phosphorus and calcium balance and expression of type IIa sodium-dependent phosphate transporter (Npt IIa) in mature rats. Wistar male rats (8-weeks old) were divided into five groups and fed diets containing 0.6% calcium plus 0.3, 0.6, 0.9, 1.2 or 1.5% phosphorus for 4 weeks. Urinary and fecal phosphorus excretions were significantly increased by the high phosphorus diets (from 0.6 to 1.5%), dependent on the amount of dietary phosphorus. The net absorption of intestinal phosphorus was also significantly increased by high phosphorus diets. As a result, a negative phosphorus balance was observed in rats given the 1.2% or 1.5% phosphorus diets. Serum parathyroid hormone and 1,25-dihydroxyvitamin D₃ concentrations were increased by high phosphorus diets. In addition, high phosphorus diets decreased the expression of Npt IIa mRNA and protein in the renal brush border membrane. Taken together, these results suggest that diets containing 1.2 or 1.5% phosphorus plus 0.6% calcium have potentially adverse effects on phosphorus homeostasis in mature rat.

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