Radiation Effects on Bioelectric Activity of 



Nerves 



C. S. Bachofer 



University of Notre Dame, 

 Notre Dame, Indiana 



Introduction 



The objective of this presentation is to consider the eflfects of ionizing 

 radiations on the bioelectric activity of nerve fibers zn vitro and in vivo. The 

 immediate effects of irradiation on responses of nerve fibers were determined 

 by recording from the nene before, during, and, in some cases, after irradia- 

 tion. After the basic patterns of activity were estabHshed with mammaUan 

 nerve trunks, the findings were supplemented with results obtained from the 

 irradiation of single nerve fibers of invertebrates, making it possible to deter- 

 mine more precisely the basic pattern of activity of the individual fiber. To 

 determine to what extent the results observed with x-rays could be attributed 

 specifically to the ionization process itself, the results due to x-irradiation 

 were compared to those obtained with nonionizing radiation. 



Previous reports (Gerstner et al., 1955; Gerstner, 1956) have considered 

 chiefly the destructive eflfects of irradiation on nerves previously subjected to 

 radiation. For references to earlier studies, the Gerstner articles may be 

 consulted. 



Booth ct al. (1950) found that ultraviolet (UV) irradiation of the node 

 of Ran\ier of the frog sciatic nerve produced an increase in threshold and 

 ultimate block: irradiation of the internode produced an immediate decrease 

 in threshold followed by a steady increase. Pierce and Giese (1957) reported 

 a decrease in spike amplitude and sensitivity of frog and crab nerves exposed 

 to UV, but found no detectable eflfect on the refractoiy period. Boyarsky 

 (1952) noted a fall in action potential, a prolongation of refractory period, 

 and only a slight change in threshold of frog sciatic nerves. Liittgau (1956) 

 found that UV adversely aflfected action potential and threshold of single 

 nodes of Ranvier of frog sciatic nerves considerably before it affected resting 

 potential and electrotonic potential. All of these studies, with certain minor 

 discrepancies, showed the ability of radiation to destroy the responsiveness of 

 nerves, with an occasional suggestion of an increase in excitability. 



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