title: Membrane transport of Tc-99m-labeled radiopharmaceuticals, I. Brain uptake by passive transport.
abstract: The membrane transport properties of twelve Tc-99m complexes were studied by determining each complex's brain uptake index (BUI), extent of protein binding, and octanol-to-saline partition coefficient. The chelating agents used were classified as either N-substituted carbamoylmethyliminodiacetates, substituted oxines, N,N'-diesters of EDTA, or N-substituted derivatives of DTPA. The Tc-99m complexes were found to cross the blood--brain barrier in proportion to their lipophilicity. Of the four types of chelating agents tested, substituted oxines appear to be most suitable for the development of diffusible Tc-99m-labeled compounds for imaging nonexcretory organs.
mesh_terms: D000818:Animals; D001692:Biological Transport; D001812:Blood-Brain Barrier; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002614:Chelating Agents / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002854:Chromatography, Paper; D004285:Dogs; D007553:Isotope Labeling; D011485:Protein Binding; D011877:Radionuclide Imaging; D012995:Solubility; D013667:Technetium / Q000378:metabolism*
chemical_list: D002614:Chelating Agents; D013667:Technetium