Rehling M, Frøkiaer J, Poulsen E U, Marqversen J, Nielsen B V, Bacher T
Department of Clinical Physiology and Nuclear Medicine, Aarhus Municipal Hospital, Denmark.
Clin Physiol. 1995 Jan;15(1):57-71. doi: 10.1111/j.1475-097x.1995.tb00430.x.
An invasive comparative study of some pharmacokinetic aspects of 99mTc-mercaptoacetyltriglycine (MAG3), 131I-orthoiodohippurate (OIH), and 125I-iothalamate (iothalamate) was performed in six pigs 0-150 min after a simultaneous single injection (SI) and during a subsequent 90 min of continuous infusion (CI). The total plasma clearance and the renal clearance of MAG3 were about 75% that of OIH. The renal clearance of MAG3 was about 2 1/2 times the glomerular filtration rate. The distribution volume of MAG3 was 71% that of iothalamate and only 47% that of OIH. There was a significant hepatic plasma clearance of MAG3 of 5.9 ml min-1 and 3.9% of the injected dose was excreted in the bile. HPLC analysis revealed that technetium was excreted in urine and bile mainly labelled to MAG3. The average red blood cell (RBC) binding after single injection/during continuous infusion was 1.0%/2.3% for MAG3, 13.5%/9.0% for OIH, and 3.1%/5.3% for iothalamate. The binding of OIH to RBC in arterial blood increased from 8% at 1 min post-injection to 21% at 150 min post-injection. The RBC binding was higher in the renal vein, indicating incomplete back diffusion from RBC to plasma. The protein binding was 90% for MAG3, 49% for OIH and 16% for iothalamate. The renal plasma extraction of MAG3 was constant but significantly smaller after SI (0.54) than during CI (0.62). Following SI, the renal plasma extraction of OIH decreased continuously from 0.85 to 0.52, 3-150 min post-injection. On the average there was no significant difference in renal plasma extraction after SI and during CI of either OIH (0.72 versus 0.77) or iothalamate (0.26 versus 0.27). It is concluded that MAG3 is preferential to OIH as a tracer for renal function studies using a single injection technique mainly due to the constant renal extraction of MAG3.
在6头猪身上进行了一项侵入性比较研究，观察99mTc-巯基乙酰三甘氨酸（MAG3）、131I-邻碘马尿酸（OIH）和125I-碘他拉酸盐（碘他拉酸盐）在单次同时注射（SI）后0至150分钟以及随后90分钟持续输注（CI）期间的一些药代动力学方面。MAG3的总血浆清除率和肾清除率约为OIH的75%。MAG3的肾清除率约为肾小球滤过率的2.5倍。MAG3的分布容积为碘他拉酸盐的71%，仅为OIH的47%。MAG3有显著的肝血浆清除率，为5.9毫升/分钟，3.9%的注射剂量经胆汁排泄。高效液相色谱分析显示，锝主要以标记到MAG3的形式经尿液和胆汁排泄。单次注射/持续输注期间，MAG3的平均红细胞（RBC）结合率分别为1.0%/2.3%，OIH为13.5%/9.0%，碘他拉酸盐为3.1%/5.3%。OIH与动脉血中RBC的结合率从注射后1分钟的8%增加到注射后150分钟的21%。肾静脉中的RBC结合率更高，表明RBC向血浆的逆向扩散不完全。MAG3的蛋白结合率为90%，OIH为49%，碘他拉酸盐为16%。MAG3的肾血浆提取率恒定，但单次注射后（0.54）明显低于持续输注期间（0.62）。单次注射后，OIH的肾血浆提取率在注射后3至150分钟从0.85持续下降至0.52。平均而言，OIH（0.72对0.77）或碘他拉酸盐（0.26对0.27）单次注射后和持续输注期间的肾血浆提取率无显著差异。结论是，作为使用单次注射技术进行肾功能研究的示踪剂，MAG3优于OIH，主要是因为MAG3的肾提取率恒定。
