THE EFFECT OF EXCITATION ON NERVE PEKMEA15ILITY 459 



Assuming, as in the case of ^^Na, that the average plasma activity 

 ckiiing the experiment amounts to about 1/3 of the determined end acti- 

 vity, 1 mgm. dry resting nerve took up 0.01 f-igm. bromine. Similar amounts 

 oi radiobromine Mere found to l^e taken up by the basal ganglia, cere- 

 hreal cortex and the medulla oljlongata of the cat. 



Jn no single case did the stimulated nerve fail to show an enhanced 

 uptake of the ion investigated. When we compute the mean of all deter- 

 minations (13 cases) of the ratio of uptake of various ions by the stimu- 

 lated and the resting nerves, the value 1.55 zb 0.10 is obtained. The 

 uptake by the stimulated nerve was also found to be enhanced when 

 the cat was curarized before stimulation in order to avoid muscular 

 movement. 



Summary 



The effect of stimulation on the amounts of phosphate, sodium, potassium 

 and bromide taken up by the sciatic nerve of the cat was investigated with the 

 aid of radioactive isotopes as indicators. Stimulation was effected by condensor 

 shocks at a rate of 50 per sec. giving maximal motor reactions. 



In each case investigated, including the curarized animal, the stimulated nerve 

 was found to take up more labelled ions than the resting nerve, the mean ratio 

 of the uptakes being 1.55 ^ 0.10. 



References 



J. L. BoLLMAN and E. V. Flock (1943) J. Biol. Chem. 147, 155 



L. Hahn and G. Hevesy (1941) Acta Physiol. Scand. 2, 154. 



G. Hevesy and H. v. Euleb (1942) Svensk Vet. Akad. Ark. Kemi 15, A No. lo. 



G. Hevesy and O. Rebbe (1946) cf. A. Krogh (1946) Proc. Roy. Soc. B 133, 



195. 

 A. L. HoDGKiN and A. F. Huxley (1946) Nature 158, 376. 

 H. Kalckak, J. Dehlingeb and A. Mehler (1944) J. Biol. Chem. 154, 275. 

 T. R. NooNAN, W. O. Fenn and L. Haege (1941) Amer. J. Physiol. 132, 612. 



