Wan X, Fu T C, London R E
Laboratory of Molecular Biophysics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
Magn Reson Med. 1992 Sep;27(1):135-41. doi: 10.1002/mrm.1910270113.
Previous studies of MRI contrast resulting from the intracerebral administration of several contrast agents have suggested that the distribution of these agents may be dependent on the net charge. In order to further evaluate the significance of this parameter, the distribution of both aquo and CDTA-chelated lanthanide and transition metal ions in the cerebral ventricles of rats has been evaluated based on their enhancement of MRI contrast. The agents were injected directly into the lateral ventricles of Sprague-Dawley rats. Each of five different positively charged paramagnetic metal ions tested selectively enhanced the inner cellular layers of ventricular luminal wall of the rat brain, while such enhancement was absent using the corresponding negatively charged metal-CDTA complexes. The abundance of negatively charged residues on the cell surface of the inner luminal layers is suggested to be the source of the observed charge affinity. Differences in the distribution of Mn2+ ions administered intracerebrally compared with intraperitoneal (ip) injection suggest that while the first treatment may result primarily in uncomplexed aquo ions which then interact with the luminal surface, manganese ions administered ip behave more like chelated ions and are most probably complexed to transferrin.
先前对几种造影剂脑内给药产生的MRI造影的研究表明，这些造影剂的分布可能取决于净电荷。为了进一步评估该参数的重要性，基于对MRI造影的增强作用，对大鼠脑室中含水和CDTA螯合的镧系元素及过渡金属离子的分布进行了评估。将这些造影剂直接注入斯普拉格-道利大鼠的侧脑室。所测试的五种不同带正电荷的顺磁性金属离子中的每一种都选择性地增强了大鼠脑室腔壁的内层细胞层，而使用相应的带负电荷的金属-CDTA络合物时则没有这种增强。内层腔壁细胞表面带负电荷残基的丰度被认为是观察到的电荷亲和力的来源。与腹腔内（ip）注射相比，脑内给药的Mn2+离子分布的差异表明，虽然首次治疗可能主要产生未络合的水合离子，然后这些离子与腔表面相互作用，但腹腔内注射的锰离子表现得更像螯合离子，很可能与转铁蛋白络合。
