US EPA

3118913 

Journal Article 

A comparison of radiation-sensitizing ability and cell uptake for NDPP and Ro-07-0582 

Wong, TW; Whitmore, GF 

1977 

1 

Radiation Research
ISSN: 0033-7587
EISSN: 1954-2002 

HEEP/78/04649 

71 

1 

132-148 

HEEP COPYRIGHT: BIOL ABS. Activated NDPP (p-nitro-3-dimethylaminopropiophenone) was an efficient sensitizer of hypoxic mammalian cells in vitro, far better than Ro-07-0582 (1-(2-nitroimidazoyl)-3-methoxy isopropanol) on a molar basis. The situation was reversed in vivo. Determinations of uptake of radioactive drug indicated that activated NDPP was capable of rapidly accumulating in mammalian cells, but no such effect was seen with Ro-07-0582. The uptake of activated NDPP showed a strong dependence on the cell density, whereas the uptake of Ro-07-0582 was little affected by cell density. The high sensitizing efficiency of activated NDPP was due to its ability to be concentrated by cells in a form which is still capable of sensitization and that the cell density effect was largely due to the depletion of the activated form or forms of NDPP. Activated NDPP reacted with cellular consitutents, notably sulfhydryl compounds and the reaction with glutathione produced a compound which was capable of hypoxic cell sensitization. Such reaction products, which were resistant to washing, may explain the pretreatment sensitization produced by activated NDPP.