Abstract
1. The enhancement of the radiation effects on yeast cells was not always attained when the cells were treated with enzyme inhibitors before they were X-irradiated.
2. Usually, such universal inhibitors to many kinds of enzymes as urethane and K-CN are not capable of enhancing the radiation effects when they are applied before irradiation, not on by they are known as radiomimetic but even also they are known protective.
3. Contrary to the above, such specific inhibitors or anti-metabolites as vagostigmin, malonic acid and azaguanine do enhance the radiation effects when the cells are treated with them prior to irradiation.
4. As to the action mechanisms of the sensitization by these specific inhibitors, the authors are of the following opinion : As the normal substrate of enzymes are diminish ed by X-ray irradiation, the competitive inhibitors, which penetrate excessively into cells is incorporated into the enzymic reaction instead of the substrates.
5. As to the sensitization with d-glutamic acid, the authors are of the opinion that d-glutamic acid is one of the anti-metabolites to amino acid matabolism.
