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目的研究高血磷对5/6肾切除大鼠肾脏Ⅱa型钠-磷协同转运子(NaPi-2)mRNA表达的影响及司维拉姆(Renagel)的干预作用。方法42只SD大鼠,随机分为5/6肾切除加高磷饲料组(STNx+HP)(含P1.2%)、5/6肾切除加低磷饲料组(STNx+LP)(含P0.2%)、5/6肾切除加正常磷饲料组(STNx+NP)、5/6肾切除高磷饲料+Renagel组(STNx+HP+Ren)(Renagel在饲料中占2%)、假手术高磷饲料组(Sham+HP)、假手术低磷饲料组(Sham+LP)、假手术正常磷饲料组(Sham+NP)。术后14d,测定血清离子钙(iCa)、磷(P)、全段甲状旁腺激素(iPTH)、血1,25-(OH)2D3和尿磷酸盐排泄分数(FEp)。RT-PCR检测NaPi-2mRNA在肾脏的表达。结果STNx+Hp组的血P、iPTH明显高于STNx+LP组及假手术3个组(P均<0.05);上述5个组间的血iCa、1,25-(OH)2D3差异无统计学意义(P均>0.05)。STNx+LP组血P、iPTH均明显低于STNx+HP组(P均<0.05)。STNx+HP组较STNx+LP组肾NaPi-2mRNA表达明显减少(P<0.01)。STNx+HP+Ren组较STNx+HP组NaPi-2mRNA表达明显增加。结论高磷血症是促进5/6。肾切除大鼠血iPTH增高且不受钙和1,25-(OH)2D3影响的独立因素。高磷显著地降低5/6肾切除鼠肾NaPi-2mRNA表达,而司维拉姆能显著降低血磷及iPTH,增加肾NaPi-2mRNA表达。
Objective To investigate the effect of hyperphosphatemia on expression of type Ⅱa sodium-phosphate cotransporter (NaPi-2) mRNA in 5/6 nephrectomized rats and intervention of Renagel. Methods Forty-two SD rats were randomly divided into 5/6 nephrectomy plus high-phosphorus diet (STNx + HP) (P1.2%), 5/6 nephrectomy plus low-phosphorus diet (STNx + LP) P0.2%), 5/6 nephrectomy plus normal phosphorus diet (STNx + NP), 5/6 nephrectomy with high phosphorus diet + Renagel (STNx + HP + Ren) Sham + HP, sham + LP and Sham + NP were used as sham-operated sham operation group. Serum ionized calcium (iCa), phosphorus (P), total parathyroid hormone (iPTH), blood 1,25- (OH) 2D3 and urinary phosphate excretion fraction (FEp) were measured 14 days after operation. The expression of NaPi-2 mRNA in kidney was detected by RT-PCR. Results The levels of blood P and iPTH in STNx + Hp group were significantly higher than those in STNx + LP group and sham operation group (all P <0.05). There was no statistical difference in the iCa, 1,25- (OH) 2D3 between the 5 groups Significance (P> 0.05). The levels of P and iPTH in STNx + LP group were significantly lower than those in STNx + HP group (all P <0.05). The expression of NaPi-2 mRNA in STNx + HP group was significantly lower than that in STNx + LP group (P <0.01). Compared with STNx + HP group, the expression of NaPi-2mRNA in STNx + HP + Ren group increased significantly. Conclusions Hyperphosphatemia is promoted by 5/6. Nephrectomy rat blood iPTH increased and independent of calcium and 1,25 - (OH) 2D3 independent factors. High phosphorous significantly reduced NaPi-2mRNA expression in 5/6 nephrectomized rats, while sevelamer significantly reduced serum phosphorus and iPTH, and increased renal NaPi-2mRNA expression.