604 EDGAR L. GASTEIGER AND BERRY CAMPBELL 



types and should be helpful in future investigations. The 255,000 rep dose 

 to produce 37^r survival of mammalian beta fibers at room temperature 

 compares well with the 300,000 r dose reported for frog sciatic nerve (Audiat 

 et al., 1934; Gerstner, 1956). Gerstner et al. (1955) reported a considerably 

 lower blocking dose for x-irradiation of rabbit sciatic. However, in their 

 experiments the block occurred up to 1 hour after the x-ray dose had been 

 delivered, while here the irradiation was continued vmtil block. Increased 

 temperature markedly reduced the 37% survival dose to 60,000 rep. Al- 

 though a similar efTect has been reported for the frog sciatic nerve in 

 response to x-ray (Audiat and PifTault, 1934), the efTect was not nearly as 

 profound as seen here for mammalian nerve. 



Summary 



The compound action potentials of cat sural, saphenous, and vagus nerves 

 were recorded during irradiation of a short length of the nerves with beta 

 rays from a small bulb filled with radon. 



For sural and saphenous nerve fibers, the order of decreasing sensitivity 

 to irradiation was delta, gamma, and beta. Less conclusive results show the 

 C fibers to be less than or equal to the deltas in sensiti\'ity, but greater than 

 the betas. 



Slow fibers ( delta and B ) of the vagus nerve were more sensitive than the 

 fast A fibers. The va^al C' fibers were less sensitve than the A and B fibers. 



References 



Audiat, J. 1932. Action du rayonnenient x siir les paranietrcs d'excitabilite du nerf. 



Compt. rend soc. biol. 110, 365. 

 Audiat, J., and Piffault, C. 1934. .'\rtion des rayons x sur le nerf isole. Phenomene de 



latence. Courbes thermiqnes. Compt. rend. soc. biol. 116, 1270. 

 Audiat, J., Auger, D., and Fessard, A. 1934. Etude des potentials d'action des nerfs 



soumis au rayonnement x. Comparison avec Taction des rayons ultra-violets. 



Compt. rend. soc. biol. 116, 880. 

 Bachofer, C. S., and Gautereaux, M. E. 1959. X-ray effects on single nerve fibers. 



/. Gen. Physiol. 42, 723-735. 

 Bachofer, C. S., and Gautereaux, M. E. 1960. Bioelectric activity of mammalian 



nerves during x-irradiation. Radiation Research 12, 575-586. 

 Gasteiger, E. L. 1951. EflPccts of beta rays on mammalian nerve action potentials. 



Federation Proc. 10, 48. 

 Gasteiger, E. L. 1959. The radioresistance of peripheral nerve. In "Neurological 



Sciences," Proc. 1st Inter. Congr., Brussels, 1957 (L. van Bogaert and J. Rader- 



mecker, eds.). Vol. 4: Neuropathology, pp. 130-136. Pergamon, New York. 

 Gerstner, H. B. 1956. Eflfect of high-intensity x-radiation on the A group fibers of 



the frog's sciatic nerve. Am. J. Physiol. 184, 333-337. 



