It is obvious that irradiation increases local oxygen uptake. Because the oxygen supply is not altered, a decrease in local oxygen partial pressure may develop. This state may be called relative hypoxia. If the metabolism is altered for a period of at least 24 hrs an increase in angiogenic mitogens, inducing angiogenesis will occur. Presumably this is the mechanism underlying the therapeutic effect of radiotherapy in benign disease.
Animals Chick Embryo