Binding of misonidazole to hypoxic cells in monolayer and spheroid culture: evidence that a side-chain label is bound as efficiently as a ring label.

The binding of ring-labelled and side-chain labelled misonidazole to hypoxic cells in monolayer and spheroid cultures of mammalian cells has been compared. The kinetics and patterns of binding for the two labelled compounds are indistinguishable. This finding has implications for the mechanism of binding and for the design of misonidazole analogues which might be used to identify hypoxic zones in tumours.