THE EFFECT OF EXCITATION ON NERVE PERMEABILITY 



451 



a rabbit of the same weight, tlie average specific activity of the inorganic 

 P in the plasma works out in a 3-minute experiment to be about 3 times 

 that of the experimentally determined amount. For the amount of P 

 penetrating during 3 mhiutes into the r(\sling nerve tissue (cf. Tables 



0.08 0.09 

 3 and 4) we hence obtain the values and as percentage activity 



of nerve P to plasma P. fn the experiment recorded in Table 1 the 



0.22 

 approximate value is obtained. As discussed above the average 







specific activity of the plasma P is higher than its end value which 

 was determined experimentally. To account for this decrease, we have 

 in the experiment taken 5 minutes to divide the percentage activity 

 of nerve P to plasma P with the figure 6 which should give an approx- 

 imately correct value. 



The amount of plasma P passing into 1 gm fresh resting nerve tissue 

 in the course of 1 minute proves on the average to be 0.01 per cent of 

 the total P of the nerve tissue, thus about 0.4 //gm. 



The amount of phosphorus penetrating in 1 minute into the nerve 

 tissue is smaller than the corresponding amount penetrating into the 

 muscle cells. Kalckar et at. (1944) estimate that, in the course of 

 1 minute, 1 f^gni phosphorus penetrates into the cells of 1 gm fresh muscle 

 tissue of the rat. A simular figure is reported by Hevesy and H. v. 

 EuLER (1942). 



Sodium Permeability 



In these experiments labelled sodium with an activity of about 0.5 

 millicurie was injected into the circulation. The cat was killed 5 minutes 

 after the injection. In each experiment, as seen in Table 5, the irritated 

 nerve was found to take up more ^^Na than the resting nerve. 



Tablk 5. — Uptake of '^*Na by Sciatic Nervi: 



Assuming 1 mgm. dry plasma to contain 40 y"gm. sodium and the 

 mean activity of sodium during the 5-minute experiment to amount to 3 



