LOW PHOSPHATE DIET UP-REGULATES THE RENAL AND INTESTINAL SODIUM-DEPENDENT PHOSPHATE TRANSPORTER IN VITAMIN-D-RESISTANT HYPOPHOSPHATEMIC MICE
LOW PHOSPHATE DIET UP-REGULATES THE RENAL AND INTESTINAL SODIUM-DEPENDENT PHOSPHATE TRANSPORTER IN VITAMIN-D-RESISTANT HYPOPHOSPHATEMIC MICE
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DOI：
10.3181/00379727-205-43692
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发表时间：
1994-02-01
影响因子：
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通讯作者：
GHISHAN, FK
中科院分区：
文献类型：
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作者：
NAKAGAWA, N;GHISHAN, FK
大鼠的膳食 P-i 限制会增加肾脏和空肠对无机磷酸盐 (P-i) 的吸收。 Hyp 小鼠的 Na+ 依赖性磷酸盐转运蛋白缺陷位于肾脏；然而，Hyp 小鼠的肾脏和空肠对低 P-i 饮食的适应尚未得到很好的表征。因此，目前的研究旨在表征Hyp小鼠肾脏和空肠Na+依赖性磷酸盐转运的适应情况，并将其与正常小鼠进行比较。与对照 P-i 饮食饲养的小鼠的相应值相比，低 P-i 饮食显着增加了肾刷状缘膜 (BBM) 磷酸盐摄取初始速率的斜率 (0.035 vs 0.017) (P < 0.01)。 Hyp 小鼠肾 Na+ 依赖性磷酸盐摄取动力学显示，在低 P-i 饮食和对照 P-i 饮食中，V-max 分别为 1.00 +/- 0.01 和 0.46 +/- 0.02 nmoles/mg 蛋白质/l5 秒 (P < 0.01)，而 K-m 值分别为 0.07 +/- 0.04 和 0.02 +/- 0.01。对正常小鼠肾 BBM 进行的类似动力学分析显示，低 P-i 饮食和对照 P-i 饮食的 V-max 分别为 2.4 +/- 0.17 和 1.18 +/- 0.09 (P < 0.01)，K-m 分别为 0.07 +/- 0.03 和 0.08 +/- 0.03。同样，低P-i饮食显着增加了肠道磷酸盐吸收初始速率的斜率（0.013和0.007）（P <0.01）。 Hyp 小鼠空肠 Na+ 依赖性磷酸盐摄取动力学显示，在低 P-i 饮食和对照 P-i 饮食中，V-max 分别为 0.36 +/- 0.01 和 0.2 +/- 0.02 nmoles/mg 蛋白质/l5 秒 (P < 0.01)，K-m 分别为 0.13 +/- 0.06 和 0.06 +/- 0.01 mM。正常小鼠空肠 BBM 的动力学分析显示，低 P-i 饮食和对照 P-i 饮食中的 V-max 分别为 0.47 +/- 0.04 和 0.18 +/- 0.01 nmoles/mg 蛋白质/15 秒 (P < 0.01)，K-m 分别为 0.16 +/- 0.04 和 0.11 +/- 0.01。数据表明，低磷酸盐饮食上调低磷血症小鼠肾脏和空肠 Na+ 依赖性磷酸盐协同转运蛋白的 V-max。
Renal and jejunal absorption of inorganic phosphate (P-i) increases with dietary P-i restriction in the rat. The defect in Na+-dependent phosphate transporter has been localized to the kidney of the Hyp mice; however, the adaptation to low-P-i diet in both kidney and jejunum of the Hyp mice has not been well characterized. Therefore, the current studies were designed to characterize the adaptation of renal and jejunal Na+-dependent phosphate transport in the Hyp mice and compare it with normal mice. Low-P-i diet significantly increased the slope of the initial rate of renal brush border membrane (BBM) phosphate uptake compared with corresponding values in mice raised on control-P-i diet (0.035 vs 0.017) (P < 0.01). Kinetics of renal Na+-dependent phosphate uptake in Hyp mice showed a V-max of 1.00 +/- 0.01 and 0.46 +/- 0.02 nmoles/mg protein/l5 sec in low- and control-P-i diets, respectively (P < 0.01), whereas, K-m values were 0.07 +/- 0.04 and 0.02 +/- 0.01, respectively. Similar kinetic analysis in renal BBM of normal mice showed a V-max of 2.4 +/- 0.17 and 1.18 +/- 0.09 (P < 0.01) and K-m of 0.07 +/- 0.03 and 0.08 +/- 0.03 on low and control P-i diets, respectively. Similarly, low-P-i diet significantly increased the slope of the initial rate of intestinal phosphate uptake (0.013 and 0.007) (P < 0.01). Kinetics of jejunal Na+-dependent phosphate uptake in Hyp mice showed a V-max of 0.36 +/- 0.01 and 0.2 +/- 0.02 nmoles/mg protein/l5 sec, (P < 0.01) and K-m of 0.13 +/- 0.06 and 0.06 +/- 0.01 mM in low- and in control-P-i diet, respectively. Kinetic analysis in jejunal BBM of normal mice showed a V-max of 0.47 +/- 0.04 and 0.18 +/- 0.01 nmoles/mg protein/15 sec (P < 0.01) and K-m of 0.16 +/- 0.04 and 0.11 +/- 0.01 in low- and control-P-i diets, respectively. The data indicates that low-phosphate diet upregulates the V-max of the renal and jejunal Na+-dependent phosphate cotransporter in the hypophosphatemic mice.