BMS181321 accumulation in rodent and human cells: the role of P-glycoprotein.

A 2-nitroimidazole with a side chain that contains technetium-99m as a chelate, BMS181321, is undergoing evaluation as an imaging agent for myocardial and cerebral ischaemia, as well as a diagnostic probe for hypoxic cells in solid tumours. Its accumulation in hypoxic and aerobic populations of three lines of Chinese hamster ovary cells of differing P-glycoprotein status, as well as one rat and two human cell lines has been determined. There was selective accumulation of BMS181321 in hypoxic vs aerobic cells. P-glycoprotein level was not a factor in this accumulation and hypoxic human cells accumulated BMS181321 more rapidly than the rodent cells. These results indicate P-glycoprotein levels in tumour cells will not confound the use of BMS181321 as a hypoxic cell marker.