本文通过大鼠饲喂试验研究了不同磷水平对磷吸收的影响，旨在进一步揭示无机磷的吸收机理。试验选用120只体重相近的昆明大白鼠，随机分成4个处理，每处理5个重复，每个重复6只大白鼠，分别饲喂含磷（总磷）0.2%、0.4%、0.6%、0.8%的饲粮，试验期14 d，测定血钙血磷、骨钙骨磷及不同肠段Na+/PiⅡb载体转运蛋白mRNA表达量和磷的吸收等指标。结果表明，0.2%低磷组回肠、空肠、十二指肠Na+/PiⅡb载体转运蛋白mRNA表达量分别是0.6%磷水平组的3.10（P＜0.01）、3.07（P＜0.01）、2.17倍（P＜0.05）；但肾脏中Na+/PiⅡb mRNA表达量比其他3个磷水平组分别低9.19、12.86、23.15倍，差异均极显著（P＜0.01）；0.2%低磷组中回肠Na+/PiⅡb mRNA表达量分别是空肠、十二指肠和肾脏的1.34（P＞0.05）、3.43（P＜0.05）和95.53倍（P＜0.01）；肾脏中Na+/PiⅡb mRNA的表达量最低，分别比空肠、十二指肠低70.92、27.85倍，差异均极显著(P＜0.01)。0.2%低磷组磷吸收比0.6%和0.8%磷水平组分别提高了22.11%（P＜0.05)和19.35%（P＜0.05)，同时还提高了血清中维生素D3含量（P＜0.05)。研究表明，低磷提高了小肠中Na+/PiⅡb载体转运蛋白mRNA表达量和磷的吸收，且在低磷条件下，大鼠Na+/PiⅡb载体转运蛋白mRNA表达量以回肠最高，肾脏最低。

A rats feedig trial was conducted to investigate the effects of phosphorus levels on phosphorus uptake to reveal the mechanism of phosphate (Pi) uptake. One hundred and twenty male Kunming rats with body weight of 18 to 22 g were randomly divided into 4 treatments, and each treatment consisted of 5 replicates with 6 rats per replicate. The 4 treatments were fed the basal diets supplemented with 0.2%, 0.4%, 0.6% and 0.8% total phosphate. The experiment lasted for 14 days. Calcium (Ca) and Pi concentration in bone and serum and Na+/PiⅡb mRNA expression were determined. It showed that Na+/PiⅡb mRNA expression was 3.10 （P＜0.01), 3.07 （P＜0.01) and 2.17 （P＜0.05) folds as that of normal Pi treatment in ileum, jejunum and duodenum, respectively, but 9.19 （P＜0.01), 12.86 (P＜0.01) and 23.15 (P＜0.01) folds in kidney lower than that of other three treatments. Na+/PiⅡb mRNA expression was the highest in ileum, and that of 0.2% Pi treatment was 1.34 (P＞0.05), 3.43 (P＜0.05） and 95.53 （P＜0.01) folds as in jejunum, duodenum and kidney, respectively. Na+/PiⅡb mRNA expression of 0.2% Pi treatment was the lowest in renal, which was 70.92 (P＜0.01) and 27.85 (P＜0.01) folds lower than that in jejunum and duodenum, respectively. Pi uptake of 0.2% Pi treatment was 22.11% and 19.35% higher than that of 0.6% Pi and 0.8% Pi treatments (P＜0.05), respectively, and VD3 content in serum was significantly higher than that in the other three treatments （P＜0.05). The results indicate that Na+/PiⅡb mRNA expression and Pi uptake in ileum and jejunum are significantly increased by low Pi, while those in renal are decreased. The expression of Na+/PiⅡb mRNA is the highest in ileum, and the lowest in renal under low phosphate.［Chinese Journal of Animal Nutrition, 2010，22（4）:1000-1006］