DISCUSSION 213 



127. Richmond, J. E., K. I. Altman, and K. Salomon, J. Biol. Chem., 190: 817, 1951. 



128. Richmond, J. E., K. I. Altman, and K. Salomon, Science, 113: 404, 1951. 



129. Duryee, W. R., Ann. N. Y. Acad. Sci., 50: 920, 1950. 



130. Carlson, J. G., M. L. Snyder, and A. Hollaender, J. Cellular Camp. Physiol., 

 33: 365, 1949. 



131. Lourau, M., and O. Lartigue, Arch. Sci. Physiol, 5: 83, 1951. 



132. Lourau, M., and O. Lartigue, Compt. rend., 232: 1144, 1951. 



133. Hollaender, A., G. E. Stapleton, and F. L. Martin, Nature, 167: 103, 1951. 



134. Crabtree, H. G., and W. Cramer, Proc. Roy. Soc. London, B113: 238, 1933. 



135. Hayden, B., and L. Smith, Genetics, 34: 26, 1949. 



136. Crabtree, H. G., and W. Cramer, Proc. Roy. Soc. London, B113: 226, 238, 1933. 



137. Forssberg, A., personal communication. 



138. Sparrow, A. H., Ann. N. Y. Acad. Sci., 51: 1508, 1951. 



139. Giles, N. H., and A. V. Beatty, Genetics, 35: 666, 1950. 



140. Gaulden, M. E., and M. Nix, Genetics, 35: 665, 1950. 



141. Mottram, J. C, Brit. J. Radiol., 6: 615, 1933. 



DISCUSSION 

 Patt: 



Concerning the relationship between the rate of metabolism and radio- 

 sensitivity, I should like to point out that, although there is considerable evidence 

 which indicates that the level of metabolism after irradiation influences the 

 effect, evidence relating to the influence of metabolic rate during irradiation is 

 equivocal. In the frog, for example, altering temperature during irradiation 

 does not influence the response. Likewise, depriving the frog of oxygen before 

 and during exposure to x-rays is without effect. 



Regarding the protective action of cysteine, I believe that we nmst not lose 

 sight of the fact that cysteine protection against x-rays may not necessarily be 

 related to the neutralization of free radicals. It is not unlikely that cysteine and 

 anoxia effects in mammals are similar and are related to some change in the 

 pathways of metabolism. In view of the discrepancy between the frog and the 

 rat in regard to the influence of temperature and anoxia, we plan to determine 

 whether cysteine will protect the frog.* 



Hevesy: 



Patt's experiments are most interesting and show that the frog is different 

 from the mouse with regard to the temperature effect. The frog has a low meta- 

 bolic rate. In mammals with a high metabolic rate the situation is fundamen- 

 tally different, and I feel that the initial metabolic rate in the mammal has 

 some effect on the response to radiation. In the frog, if the temperature is 



* A protective effect of anoxia has been demonstrated in recent studies with frogs 

 (D. E. Smith, E. B. Tyree, and H. M. Patt, unpublished data). The early failure 

 to induce resistance in this species with anoxia may have been due to some latent 

 infection in the animals, since protection was observed subsequently when strepto- 

 mycin was added to the water or when the radiation dosage was decreased. 



