有机介质中^(99)Tc^mO_4^-非胶体还原产物的制备及其性质研究

The generation and physical,chemical, biological analysis of the reduced noncolloidal^(99)Tc^mO_4^-products

目的研究能在肿瘤中浓聚的^(99)Tc^mO_4^- 非胶体还原产物(^(99)Tc^m-Rs)的物理化学特性和生物学表现。方法采用乙腈与 Na^(99)Tc^mO_4 洗脱液混合蒸发除去水,在各种有机溶剂中,用氯化亚锡还原 Na^(99)Tc^mO_4。对^(99)Tc^m-Rs 进行薄层层析(TLC)、纸电泳、液相分配系数、滤膜通过特性研究,对类似物非胶体还原铼(Re-Rs)做元素分析。并对 H460细胞摄取^(99)Tc^m-Rs 和^(99)Tc^m-Rs 在 SD 大鼠体内分布、在肿瘤内分布及在缺血心肌内分布进行研究。结果在乙腈中还原Na^(99)Tc^mO_4可以获得高产率的^(99)Tc^m-Rs(>90%)。^(99)Tc^m-Rs 的物理、化学性质和生物学特征与^(99)Tc^mO_4^- 不同,而且不是有机化学反应产品。^(99)Tc^m-Rs 对乏氧细胞和缺血组织有亲和作用。静脉注射^(99)Tc^m-Rs 后2和18 h,在 H460肿瘤中,肿瘤/血液放射性比值分别为3.05±0.34和8.07±1.19,肿瘤/骨骼肌放射性比值分别为10.38±1.21和20.55±2.80。缺血心肌也明显摄取^(99)Tc^m-Rs。乏氧、pH 值降低和钙离子累积浓度增加,H460细胞摄取^(99)Tc^m-Rs 随之增加,乏氧和钙离子浓度增加能提高^(99)Tc^m-Rs 对二巯丙磺酸钠的标记率。以乙腈为展开剂,硅胶 TLC 结果显示^(99)Tc^m-Rs有2种成分,Rf 值分别为1.0和0.78,后者在正常和肿瘤组织中分布与^(99)Tc^mO_4^-无差异。结论 ^(99)Tc^m-Rs 是^(99)Tc^mO_4^- 在有机溶剂中还原或歧化反应产生的无机化合物,其制备简便,是前景较好的乏氧显像剂。

Objective It was found previously that the reduced noncolloidal 99^Tc^mO4^- products （99^Tc^m- Rs） were avid for tumors. The physical, chemical and biological characteristics of 99^Tc^m-Rs were thus investigated. Methods Water was removed from generator eluate of sodium pertechnetate （Na99^Tc^mO4 ） by a pump after adding appropriate amount of acetonitrile. Analysis of 99^Tc^m-Rs and its analogue reduced noncolloidal rhenium （Re-Rs） were performed with thin layer chromatography （TLC）, electrophoresis, dual phase distribution, membrane passing, and spectroscopy. The uptake and biodistribution of 99^Tc^m-Rs in H460 cell culture, tumor bearing SD rats and myocardial ischemic models were studied in comparison with 99^Tc^mO4^-. Images were acquired with a γ camera. Results The content of 99^Tc^m-Rs was 〉 90% when the reduction reaction was carried out in acetonitrile. The physical, chemical and biological characteristics were different between 99^Tc^m-Rs and 99^Tc^mO4^-. The organic elements （such as C, H and N） could not be identified in the main products of Re-Rs （the analogue of 99^Tc^m-Rs）. Significant accumulation of 99^Tc^m-Rs in tumors and ischemic myocardium were noted. In H460 tumor bearing mice, the activity ratios of tumor/ blood and tumor/muscle were 3.05 ± 0.34 and 10.38 ± 1.21 at 2 h after intravenous injection of 99^Tc^m-Rs. Acidification, hypoxia or adding calcium could increase H460 cells uptake of 99^Tc^m-Rs, but not 99^Tc^mO4^-. The labeling efficiency of sodium dimercaptopropane sulfonate with 99^Tc^m-Rs increased in the hypoxic and calcium loaded condition. Improvement of nonspecific binding of 99^Tc^m-RS to biomolecules under hypoxia and calcium overload condition might be the mechanism underlined. Using acetonitrile as the mobile phase, TLC showed two peaks of activities on silica gel plate with Rf value of 1.0 and 0.78 respectively, the later was similar in biodistribution to 99^Tc^mO4^- in normal tissues and tumors. Conclusions 99^Tc^m-Rs are re- duced inorganic products from 99^Tc^mO4^- in organic solvents. 99^Tc^m-RS are novel hypoxia specific agents.