Nitroimidazole adducts asmarkers fortissue hypoxia: mechanistic studies inaerobic normal tissues andtumourcells

major causeofthehighbinding rateinoesophageal mucosa, andmay notcontribute significantly tothe observed binding inother normal tissues. Ithasbeensuggested that metabolism ofnitroimidazoles byaerobic cells intumoursmightbesufficient tominimise accessofthese compounds tohypoxic regions, particularly at themicromolar concentrations currently inuse clinically. Theuptake of'251-iodoazomycin arabinoside by RIF-1andEMT6 tumourswas found tobedirectly proportional toinjected doseoverconcentrations between 0.5and501M.Labelling ofhypoxic regions inEMT6 tumoursbyhighspecific activity 3H-misonidazole at 1 JLM was foundtobesimilar tothatobtained at50;LM. Non-invasive techniques formonitoring tumourhypoxia wouldbevaluable prior toradiotherapy inorder tounderstand thenatural history oftumourhypoxia, andtoidentify individuals forwhomstandard radiotherapy islikely tobe inadequate sothatthey may beselected fortrials ofadjunctive therapies such asperfluorochemical emulsions (Teicher &