Originally published in Acta Physiol. Sccwd. 12, 261 (1946) 



45. THE EFFECT OF EXCITATION ON NERVE 



PERMEABILITY 



H. V. EULBE, U. S. V. EULEE, AND G. HeVESY 

 From the Institute of Research in Organic Chemistry, and the Physiological 

 Department of Karolinska Institute, Stockholm 



The effect of muscular exercise on the permeability of muscular tissue 

 to phosphates (Bollman and Flock, 1943 ; Hevesy and Rebbe, 1946) 

 and potassium (Hahn and Hevesy, 1941 ; Noonan, Fenn and 

 Haege, 1941) has previously been investigated by using ^^p and *^K 

 as indicators. Phosphate-permeability was found to be influenced only 

 1o a minor extent by muscular exercise, while the amount of potassium 

 was found to be increased 3 to 4 times as the result on intense muscular 

 work. 



The present communication gives the results of experiments in which 

 the effect of excitation on the permeability of the sciatic nerve for 

 ])hosphate, sodium, potassium and bromide was investigated. 



Radioactive isotopes were used as indicators. ^^^ 



EXPERIMENTAL PROCEDURE 



Cats weighing about 2 kgm were used. Chloralose, 5— 6 ml of an 1 per cent solu- 

 tion per kgm was injected into a brachial vein under ether anaestesia, except in 

 the first case (Table 1), where it was injected into the femoral vein on the stimu- 

 lated side. The sciatic nerves were exposed near the spinal cord on each side and 

 f^rushed with a forceps. Stimulation was effected by means of a thyratron stimula- 

 tor giving condenser shocks at a rate of about 50 per sec. and at a strength pro- 

 ducing about maximal motor reactions. In one experiment (sodium No 5) the 

 animal was curarised before stimulation in order to avoid muscular movements. 



The radioactive salts, dissolved in a few ml of distilled water, was injected 

 intravenously through the cannula used for the anaesthetic. In the majority 

 of cases the stimulation was carried on for 5 minutes and the active preparation 

 injected at the end of the second minute of stimulation. Immediately after the 

 stimulation a sample of hepaiinized blood was taken by heart puncture and 

 centrifugated, the plasma being used for determination of the activity. The animal 

 was killed by bleeding and the hind legs washed free of blood by perfusion with 

 Ringer's solution through a cannula in the lower part of the aorta. \Mien the 



^1^ Our thanks are due to Prof. Niels Bohr and to Prof. M. Siegbahn for tli< 

 radio-active preparations kindly put at our disposal. 



