286 



C. T. GAFFEY 



The technique for studying the emergence of Na^^ from isolated sciatic 

 nerve was similar to that described by Shanes (1954). Nerves were immersed 

 in Na^- Ringer's solution for approximately 12 hours at 10° C, brought to 

 room temperature (21° C), and irradiated in the beam of the 184-in. syn- 

 chrocyclotron. The emergence of Na'^ from the "loaded" nerves into fre- 

 quently replaced vials of inactive Ringer's was measured with a satisfactory 

 degree of accuracy (counting error less than 1%) by a scintillation spec- 

 trometer. 



Figure 9 illustrates that after an exposure to 200 krad of alpha particle 

 irradiation, there was a small decrease in the rate of movement of sodium 

 ions from the irradiated nerve when compared to its control. From 8 experi- 

 ments in which nerves were administered doses below 150 krad of alpha 

 particles, there was no evidence of an alteration in the rates of loss of Na^^ 

 as a consequence of irradiation. 



From these limited radioactive studies, it can be inferred that with alpha 

 particle irradiation in excess of 150 krad there is probably a rise in the so- 

 dium ion content of sciatic nerve due to an increase in the rate of sodium ion 

 penetration coupled with a decrease in the rate of sodium ion loss. 



In these experiments the studies on the rate of Na^' loss began 5 minutes 

 after irradiation was completed, while Na^- uptake studies started 1 hour 

 pjostirradiation. 



100 



.2 10 



40 



80 120 



Minutes 



160 



200 



Fig. 9. Decline of the Na" content (percent initial) of sheathed sciatic nerves by 

 diffusion into Ringer's solution. Each of the experimental points on the 200 krad 

 alpha particle line is the average data from 4 experiments, as are the points on the 

 control line. 



