Oxygen free radicals play a role in cellular differentiation: an hypothesis.

Evidence from a variety of sources supports the view that oxygen free radicals play a role in cellular differentiation. It is postulated that cellular differentiation is accompanied by changes in the redox state of cells. Differentiated cells have a relatively more prooxidizing or less reducing intracellular environment than the undifferentiated or dedifferentiated cells. Changes in the redox balance during differentiation appear to be due to an increase in the rate of O2- generation. Differentiated cells, in general, exhibit higher rates of cyanide-resistant respiration, cyanide-insensitive SOD activity, and peroxide concentration and lower levels of GSH as compared to undifferentiated cells. The effects of free radicals on cellular differentiation may be mediated by the consequent changes in ionic composition.