Freitas R S, Gutfilen B, da Fonseca L M, Bernardo-Filho M
Centro de Pesquisa Básica, Instituto Nacional de Câncer, Rio de Janeiro, Brasil.
Yale J Biol Med. 1996 Nov-Dec;69(6):483-8.
Secure determination of the binding of 99mTc-radiopharmaceuticals to plasma (P) and blood cell (BC) constituents can help to understand the biodistribution of radiophamaceuticals. The reported precipitation studies of blood with radiopharmaceuticals have shown that the results can not be easily compared between studies. We decided to determine the "gold standard" concentration of trichloroacetic acid (TCA) to evaluate the binding to blood elements for several radiopharmaceuticals used in routine nuclear medicine. We have studied phytic (99mTc-PHY), diethylenetriaminepentaacetic (99mTc-DTPA), glucoheptonic (99mTc-GHA) and dimercaptosuccinic (99mTc-DMSA) acids. Blood was incubated with radiopharmaceuticals, centrifuged and P and BC separated. Samples of P and BC were also precipitated with TCA concentrations (20.0, 10.0, 5.0, 1.0, 0.5 and 0.1 percent) and soluble (SF) and insoluble fractions (IF) were isolated. The percent radioactivity (percent rad) in IF-P depends on TCA concentration. It varied from 36.4 to 65.0 (99mTc-PHY), from 17.9 to 32.0 (99mTc-DTPA), from 11.5 to 38.8 (99mTc-GHA) and from 52.8 to 66.2 (99mTc-DMSA). The results for the binding of 99mTc-PHY to IF-P show that there was no differences in the percent rad when TCA concentrations of 0.1 to 1.0 percent were used. For 99mTc-DTPA, 5.0 percent is the best TCA concentration. For 99mTc-GHA, low values of percent rad bound to IF-P is found with TCA concentrations of 0.1, 0.5 and 1.0. Interestingly, with 99mTc-DMSA, high values of bound radioactivity are not dependent on TCA concentrations (0.1 to 10.0). Radioactivity in IF-BC depends on TCA concentration and it varied for 99mTc-PHY (80.1 to 54.1) and for 99mTc-GHA (85.5 to 61.7). With 99mTc-DTPA and with 99mTc-DMSA the percent rad in IF-BC seems independent of TCA concentration. We suggest that the evaluation of the binding of the various 99mTc-radiopharmaceuticals to blood constituents, using only one TCA concentration, should be avoided.
准确测定99mTc放射性药物与血浆（P）和血细胞（BC）成分的结合情况有助于了解放射性药物的生物分布。已报道的放射性药物血液沉淀研究表明，不同研究之间的结果不易比较。我们决定确定三氯乙酸（TCA）的“金标准”浓度，以评估几种常规核医学中使用的放射性药物与血液成分的结合情况。我们研究了植酸（99mTc-PHY）、二乙三胺五乙酸（99mTc-DTPA）、葡庚糖酸（99mTc-GHA）和二巯基丁二酸（99mTc-DMSA）。血液与放射性药物孵育，离心后分离出P和BC。P和BC的样品也用不同浓度的TCA（20.0%、10.0%、5.0%、1.0%、0.5%和0.1%）沉淀，并分离出可溶性（SF）和不溶性部分（IF）。IF-P中的放射性百分比（%rad）取决于TCA浓度。其范围为36.4至65.0（99mTc-PHY）、17.9至32.0（99mTc-DTPA）、11.5至38.8（99mTc-GHA）和52.8至66.2（99mTc-DMSA）。99mTc-PHY与IF-P结合的结果表明，当使用0.1%至1.0%的TCA浓度时，%rad没有差异。对于99mTc-DTPA，5.0%是最佳的TCA浓度。对于99mTc-GHA，当TCA浓度为0.1%、0.5%和1.0%时，IF-P结合的%rad值较低。有趣的是，对于99mTc-DMSA，结合放射性的高值不依赖于TCA浓度（0.1%至10.0%）。IF-BC中的放射性取决于TCA浓度，99mTc-PHY（80.1至54.1）和99mTc-GHA（85.5至61.7）的情况有所不同。对于99mTc-DTPA和99mTc-DMSA，IF-BC中的%rad似乎与TCA浓度无关。我们建议应避免仅使用一种TCA浓度来评估各种99mTc放射性药物与血液成分的结合情况。
