Decreased hypoxic toxicity and binding of misonidazole by low glucose concentration.

The modulation of the hypoxic toxicity and binding of Misonidazole (MISO) by glucose and lactate was studied by exposing exponential EMT6/Ro cells to 5 mM MISO under hypoxic conditions. The concentrations of glucose used were 0.015 mM and 5 mM, and the concentrations of lactate were 0, 3 and 10 mM. There was no significant hypoxic toxicity due to MISO in the absence of glucose. However, with 5 mM glucose, after a latent period of 0.5 hours, there was a rapid decrease in cell survival to less than 0.1% at 2.5 hours incubation in 5 mM MISO. The binding of MISO was also increased by glucose. The amount of MISO bound to cells in 0.015 mM glucose leveled off at 2 nmoles MISO/7 X 10(5) cells at 1 hour, whereas the binding in 5 mM glucose continued to increase to more than 5 nmoles MISO/7 X 10(5) cells after 3 hours incubation. There was no detectable effect of lactate on the binding of MISO to the cells either in 0.015 mM or 5 mM glucose. The high affinity of this binding was indicated by the lack of exchange of radioactive MISO with non-radioactive MISO even after 2 hours of incubation. These data showed that glucose concentrations could modify the toxicity and binding of MISO to hypoxic cells.