Vaidyanathan G, Zhao X G, Strickland D K, Zalutsky M R
Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
J Nucl Med. 1997 Feb;38(2):330-4.
The purpose of this study was to evaluate the properties of 4-fluoro-3-[131I]iodobenzylguanidine ([131I]FIBG), a potential neuroendocrine tumor and myocardial imaging radiopharmaceutical.
The binding of [131I]FIBG and [125I]MIBG was compared in vitro using the SK-N-SH human neuroblastoma cell line. The role of the active uptake-1 mechanism was investigated by determining the effect on cell binding of desipramine (DMI), ouabain, norepinephrine (NE), unlabeled MIBG and FIBG and by incubation at 4 degrees C. Finally, the tissue distributions of [131I]FIBG and [125I]MIBG were compared in normal mice.
The specific binding of [131I]FIBG remained fairly constant (45%-60%) over a 2-3-log activity range and consistently was 11%-14% higher (p < 0.05) than that of [125I]MIBG. The uptake of [131I]FIBG was reduced to 13% of control values by 1.5 microM DMI, to 31% by 1 mM ouabain, to 8% by lower temperature, to 8% by 50 microM NE and to 6% and 5% by 10 microM each of unlabeled MIBG and FIBG, respectively. The amount of [131I]FIBG retained by SK-N-SH cells was significantly higher than that of [125I]MIBG with the maximum difference observed at 72 hr. In mice, the uptake of [131I]FIBG was higher than that of [125I]MIBG not only in target tissues (heart and adrenals) but also in many other normal tissues; conversely, thyroidal uptake of [131I]FIBG was 2-3-fold lower than that of [125I]MIBG. The uptake of [131I]FIBG in the heart and adrenals was reduced by DMI.
Iodine-131-FIBG is an analog of MIBG with prolonged binding to neuroblastoma cells in vitro and retention in the myocardium in vivo.
本研究的目的是评估4-氟-3-[¹³¹I]碘苄胍（[¹³¹I]FIBG）的特性，它是一种潜在的神经内分泌肿瘤和心肌显像放射性药物。
使用SK-N-SH人神经母细胞瘤细胞系在体外比较[¹³¹I]FIBG和[¹²⁵I]MIBG的结合情况。通过测定地昔帕明（DMI）、哇巴因、去甲肾上腺素（NE）、未标记的MIBG和FIBG对细胞结合的影响以及在4℃孵育来研究活性摄取-1机制的作用。最后，在正常小鼠中比较[¹³¹I]FIBG和[¹²⁵I]MIBG的组织分布。
在2至3个对数活性范围内，[¹³¹I]FIBG的特异性结合保持相当恒定（45%-60%），并且始终比[¹²⁵I]MIBG高11%-14%（p<0.05）。1.5微摩尔DMI可使[¹³¹I]FIBG的摄取降至对照值的13%，1毫摩尔哇巴因可使其降至31%，低温可使其降至8%，50微摩尔NE可使其降至8%，10微摩尔未标记的MIBG和FIBG分别可使其降至6%和5%。SK-N-SH细胞保留的[¹³¹I]FIBG量显著高于[¹²⁵I]MIBG，在72小时时观察到最大差异。在小鼠中，[¹³¹I]FIBG不仅在靶组织（心脏和肾上腺）中的摄取高于[¹²⁵I]MIBG，而且在许多其他正常组织中也是如此；相反，[¹³¹I]FIBG在甲状腺中的摄取比[¹²⁵I]MIBG低2至3倍。DMI可降低[¹³¹I]FIBG在心脏和肾上腺中的摄取。
碘-131-FIBG是MIBG的类似物，在体外与神经母细胞瘤细胞的结合时间延长，在体内可保留在心肌中。
