Oberbauer R, Schreiner G F, Meyer T W
Department of Medicine, Palo Alto VAMC, California, USA.
Kidney Int. 1995 Oct;48(4):1226-32. doi: 10.1038/ki.1995.406.
Renal uptake of a 35S labeled 18-mer phosphorothioate oligodeoxynucleotide (molecular wt approximately 6,000) was evaluated following intravenous infusion into rats. The kidneys contained 21 +/- 3% of the infused dose at five hours after infusion and 3 +/- 1% of the infused dose at four days after infusion. The concentration of oligonucleotide was greater in the kidney than in the liver, spleen, or plasma at both intervals. Urine excretion of oligonucleotide label averaged 17 +/- 1%, 35 +/- 5%, and 64 +/- 3% of the infused dose at five hours, one day, and four days after infusion. Electrophoresis (PAGE) showed that oligonucleotide was retained in the kidney was the intact 18-mer at both five hours and four days after infusion, while full size oligonucleotide was not found in the urine at either interval. Light microscopic autoradiography showed that oligonucleotide uptake was most prominent in the early proximal tubule. Electron microscopic autoradiography indicated that oligonucleotide was not confined to the brush border or endocytic-lysosomal pathway. Micropuncture studies showed that the tubule fluid to plasma concentration ratios of oligonucleotide label averaged 7 +/- 3% in Bowman's space and 6 +/- 2% in the distal tubule. Despite restriction of filtration by plasma protein binding, as indicated by the low Bowman's space to plasma concentration ratio, the calculated tubular reabsorption rate for oligonucleotide was sufficient to account for the large amount of oligonucleotide found in the kidney after intravenous infusion. These results indicate that the proximal tubule plays a prominent role in the disposition of intravenously infused oligonucleotide, and raise the possibility that oligonucleotides could exert antisense effects in this nephron segment.
将一种35S标记的18聚体硫代磷酸酯寡脱氧核苷酸（分子量约6000）静脉输注到大鼠体内后，评估其肾脏摄取情况。输注后5小时，肾脏中含有输注剂量的21±3%，输注后4天含有输注剂量的3±1%。在这两个时间点，肾脏中寡核苷酸的浓度均高于肝脏、脾脏或血浆中的浓度。输注后5小时、1天和4天，寡核苷酸标记物的尿排泄量平均分别为输注剂量的17±1%、35±5%和64±3%。电泳（PAGE）显示，输注后5小时和4天，保留在肾脏中的寡核苷酸均为完整的18聚体，在这两个时间点的尿液中均未发现全长寡核苷酸。光学显微镜放射自显影显示，寡核苷酸摄取在近端小管早期最为显著。电子显微镜放射自显影表明，寡核苷酸并不局限于刷状缘或内吞-溶酶体途径。微穿刺研究表明，寡核苷酸标记物在鲍曼间隙中的肾小管液与血浆浓度比平均为7±3%，在远端小管中为6±2%。尽管血浆蛋白结合限制了滤过，如鲍曼间隙与血浆浓度比低所示，但计算出的寡核苷酸肾小管重吸收率足以解释静脉输注后在肾脏中发现的大量寡核苷酸。这些结果表明，近端小管在静脉输注寡核苷酸的处置中起重要作用，并增加了寡核苷酸可能在该肾单位段发挥反义作用的可能性。
