^(99m)Tc-octreotide的标记及受体分析

Preparation and In Vitro Evaluation of Tc-99m Labeled Octreotide

目的探讨直接法标记99mTc-octreotide的方法学及其与大鼠脑皮质细胞的亲和力。方法用直接法标记99mTc-octreotide,探讨其最佳标记条件;并以~99mTc-octreotide作为配基,检测大鼠脑皮质细胞与其结合的平衡解离常数。结果99mTc—octreotide标记率为53％～57％,经Sephadex G-10纯化后放化纯大于95％;受体分析显示大鼠脑皮质细胞与99mTc-octreotide保持了较高的亲和力(Kd=10.4nM)。结论 本标记方法是可行的,99mTc—octreotide有希望作为具有临床实用价值的生长抑素受体显像剂。

Objective To establish the method of directly labeling octreotide with 99mTc, and explore the affection factors to its radiochemical purity, and the in vitro receptor binding affinity of 99mTc-oc-treotide. Method The octreotide was reduced using the ascorbic acid method, and 99mTc reduced with a fresh solution of Na2S2O4. The affection of temperature, pH of ascorbic acid and the buffer to radio-chemical purity was determined. The in vitro somatostatin receptor (SSTR)-binding affinity of 99mTc-octreotide purified by Sephadex G10, was confirmed by Scatchard analyses using SD rats brain cortex cell.Results 99mTc-octreotide were prepared in 53-57% radiochemical yield, after purified, radio-chemical purity >95% , and it has a Kd = 10.4 nM , and Bmax = 29. 4fmol/μg. Conclusion The method of directly labeling octreotide with 99mTc is available, and 99mTc-octreotide is a promising radiotracer for the clinical detection of SSTR-expressing tumor by radionuclide scintigraphy.