Katsumata Shin-ichi, Masuyama Ritsuko, Koshihara Moyuru, Matsuzaki Hiroshi, Uehara Mariko, Suzuki Kazuharu
Department of Nutritional Science, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan.
Biofactors. 2004;22(1-4):33-7. doi: 10.1002/biof.5520220106.
To determine the parathyroid hormone (PTH) action on kidney and bone by high phosphorus (P) diet, this study investigated PTH/PTH-related peptide (PTHrP) receptor mRNA expression in 6-week-old parathyroidectomized (PTX) rats received constant amount of PTH. To maintain serum PTH levels equally to sham operated rats, PTX rats were constantly exposed to rPTH (1-34) and fed a control diet (0.3% P) and a high P diet (1.2% P) for 7 days, respectively. There were no significant differences in serum PTH (1-34) concentration in rats fed the control diet. In sham groups, serum PTH concentrations, both (1-84) and (1-34) fragments, were increased in rats fed the high P diet than in rats fed the control diet. Urinary excretions of P and C-terminal telopeptides of type I collagen were significantly increased in both PTX and sham rats by the high P diet. PTH/PTHrP receptor mRNA expression in kidney and femur was not changed in both PTX and sham rats by the high P diet. In conclusion, high P diet did not change PTH action in PTX rats and increased urinary excretion of P and bone resorption regardless of PTH action.
