Canalejo A, Hernández A, Almadén Y, Concepción M T, Felsenfeld A, Torres A, Rodríguez M
Unidad de Investigación, Servicio de Nefrología Hospital Universitario Reina Sofía, Córdoba, Spain.
Nephrol Dial Transplant. 1998;13 Suppl 3:19-22. doi: 10.1093/ndt/13.suppl_3.19.
High extracellular phosphorus directly increases parathyroid hormone (PTH) secretion and gene transcription. The present study evaluates the effect of high phosphorus diet on the parathyroid cell cycle in rats with normal renal function. Rats were divided into two groups, receiving either a high phosphorus diet (HPD, P=1.2%) or a normal phosphorus diet (NPD, P=0.6%). The dietary calcium content was 0.6% in both diets. Rats were pair fed and sacrificed on days 0, 1, 5, 10 and 15 after initiation of the diet. The parathyroid glands were removed and parathyroid cells dispersed for evaluation of cell cycle and apoptosis by flow cytometry. Serum calcium, phosphorus, PTH and calcitriol were measured. As compared with NPD, the ingestion of a HPD resulted in an increased number of cells in the S phase of the cell cycle from day 1 to 10 (1.2+/-0.09% vs 0.6+/-0.04% for day 1, 1.2+/-0.11% vs 0.6+/-0.06% for day 5 and 1.0+/-0.09% vs 0.5+/-0.04% for day 10, P<0.01). By day 15, the percentage of cells in the S phase in NPD and HPD were not different. In the rats fed the HPD, serum PTH increased significantly from day 5 through 15 (P<0.01). Parathyroid cell apoptosis was minimal and unaffected by the diet. At day 15, the parathyroid gland size in HPD was increased by 27% as compared with NPD (P<0.05). This increase should be attributed to cell proliferation since parathyroid cell size remained unchanged. Serum calcitriol and calcium were not significantly different in the two groups. In HPD, an increase in serum phosphorus was observed only on day 1. The results show that an HPD results in the stimulation of the parathyroid cell cycle independently of changes in calcium and calcitriol.
高细胞外磷直接增加甲状旁腺激素（PTH）的分泌和基因转录。本研究评估高磷饮食对肾功能正常大鼠甲状旁腺细胞周期的影响。将大鼠分为两组，分别给予高磷饮食（HPD，磷含量为1.2%）或正常磷饮食（NPD，磷含量为0.6%）。两种饮食中的钙含量均为0.6%。大鼠成对喂养，并在饮食开始后的第0、第1、第5、第10和第15天处死。取出甲状旁腺，分散甲状旁腺细胞，通过流式细胞术评估细胞周期和细胞凋亡。检测血清钙、磷、PTH和骨化三醇。与NPD组相比，从第1天到第10天，HPD组细胞周期S期的细胞数量增加（第1天：1.2±0.09%对0.6±0.04%，第5天：1.2±0.11%对0.6±0.06%，第10天：1.0±0.09%对0.5±0.04%，P<0.01）。到第15天，NPD组和HPD组S期细胞的百分比没有差异。在喂食HPD组大鼠中，从第5天到第15天血清PTH显著升高（P<0.01）。甲状旁腺细胞凋亡极少，且不受饮食影响。在第15天，与NPD组相比，HPD组甲状旁腺大小增加了27%（P<0.05）。这种增加应归因于细胞增殖，因为甲状旁腺细胞大小保持不变。两组血清骨化三醇和钙没有显著差异。在HPD组中，仅在第1天观察到血清磷升高。结果表明，高磷饮食可独立于钙和骨化三醇的变化刺激甲状旁腺细胞周期。
