Richmond R C, Farrell N P, Curphey T J, Mahtani H K
Department of Radiation Oncology, Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire 03756.
Radiat Res. 1989 Dec;120(3):416-29.
Rhodium(II) binuclear complexes were surveyed for potentiation of radiation-induced cell killing of hypoxic and fully oxic Salmonella typhimurium cells. The Rh2 tetracarbonate ion substantially potentiated hypoxic cell radiation sensitivity. Phosphate interfered with this potentiation. In the latter two respects, radiation potentiation by Rh2 tetracarbonate is similar to that found for Rh2 tetracarboxylates. Amines such as ammonia, methylamine, ethylamine, n-propylamine, and n-butylamine were examined with both Rh2 tetracarbonate and tetraacetate complexes. With Rh2 tetraacetate in phosphate-buffered saline, these amines variably increased radiation potentiation to a maximum of nearly that seen by Rh2 tetraacetate alone in the absence of phosphate. With Rh2 tetracarbonate, particular amines were found to either enhance or restrict radiation potentiation. Results as a whole support the hypothesis that a radiolytic Rh species initiated in a one-electron reduction process external to the cell is responsible for the potentiation by Rh2 complexes in bacteria. Phosphate interference of potentiation by Rh2 tetracetate appears to be limited competitively by amines, suggesting that axial associations of phosphate with the Rh2 center may be involved in the inhibition of radiation potentiation. Of interest in this regard is the finding that 5'-adenosinemonophosphate eliminates the potentiation seen with Rh2 tetraacetate.
对铑（II）双核配合物进行了研究，以考察其对缺氧和完全有氧的鼠伤寒沙门氏菌细胞辐射诱导杀伤作用的增强效果。碳酸铑（II）四聚体离子显著增强了缺氧细胞的辐射敏感性。磷酸盐会干扰这种增强作用。在这后两个方面，碳酸铑（II）四聚体的辐射增强作用与四羧酸铑（II）的情况相似。研究了氨、甲胺、乙胺、正丙胺和正丁胺等胺类与碳酸铑（II）四聚体和四乙酸铑（II）配合物的作用。在磷酸盐缓冲盐溶液中，这些胺类与四乙酸铑（II）作用时，会不同程度地增加辐射增强作用，最高可达在无磷酸盐情况下四乙酸铑（II）单独作用时的近最大值。与碳酸铑（II）四聚体作用时，发现特定的胺类会增强或限制辐射增强作用。总体结果支持这样一种假说，即在细胞外部单电子还原过程中引发的辐射分解铑物种是细菌中铑（II）配合物增强辐射作用的原因。磷酸盐对四乙酸铑（II）增强作用的干扰似乎受到胺类的竞争性限制，这表明磷酸盐与铑（II）中心的轴向结合可能参与了对辐射增强作用的抑制。在这方面，有意思的是发现5'-单磷酸腺苷消除了四乙酸铑（II）所见的增强作用。
