The Effects of Ionizing Radiation on Spinal 

 Cord Neurons* 



Makoto Sato, George Austin, and Walter Stahl 



University of Oregon Medical School, 

 Portland, Oregon 



There are numerous reports in the literature on the acute effects of 

 radiation on conditioned reflexes and on the electroencephalogram (Yanson, 

 1959; Gorizontov, 1959; Bryukhanov and Lomonos, 1954). Most of these 

 state that after single whole body irradiation (Livanov and Biryukov, 1959; 

 Tsipin and Grigoryev, 1960). or head irradiation (Sercov, 1955), there was 

 an initial increase and subsequent depression of "cortical bioelectric activity." 

 Brooks (1956) found depression in the EEG of monkeys after one minute of 

 whole body irradiation at 1,000 r per minute. Irradiation of rate peripheral 

 nerves at 6,000 r per minute gave increased amplitude and conduction velocity 

 after 5 minutes of exposure (Lott, 1956). Conduction velocity in frog nerve 

 (Gerstner and Orth, 1955) was found slightly depressed only after 75 kr, 

 and not in less than 2 hours. The only work found on single nerve fibers 

 was by Bachofer and Gautereaux (1959) on the effects of acute irradiation 

 on single giant nei"ve fibers of the earthworm i?i vitro during exposure at 

 6 kr per minute. During the first 15-20 minutes, there was a significant 

 increase in amplitude, and thereafter the amplitude progressively fell below 

 normal. 



From these reports it is evident that there is varied opinion as to the 

 acute effects of small doses of irradiation. For this reason, we have under- 

 taken to investigate the effects of such irradiation on the spinal cord 

 neurons of the cat. 



Methods 



Decerebrated cats were fixed on a mounting rack and maintained under 

 artificial respiration. For further immobilization, 3% ^-tubocurarine was 



* This work was supported by a grant from the Atomic Energy Commission to the 

 University of Oregon Medical School. 



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