966 ADVENTURES IN RADIOISOTOPE RESEARCH 



form distribution of the injected radio-sodium in the extracellular fluid 

 of the body is not reached, the activity of the foot increases. In indi- 

 viduals with no vascular disturbance this stage is reached after the lapse 

 of 45 minutes. Curves indicating the increase in the activity of the foot 

 with time both in the normal and in the diseased organism are shown 

 in Fig. 2. 



For patients with various vascular disorders the curves may be within, 

 above, or below the normal region. In the curves, solid symbols represent 

 counts against the right foot, open ones against the left foot. The chart 

 shows data from a patient suffering from severe hypertension relieved 

 by bilateral thoracolumbar symphathectomy. The lowest curve (circles) 

 represents a test made before the operation. The two upper curves; 

 (squares and triangles) show the result of tests made two months and two 

 years, respectively, after operation. They demonstrate the far-reaching 

 change in the circulation of sodium ions produced by the operation. 



Information on the effectiveness of blood flow can be obtained by 

 measuring the rapidity of disappearance of radio-sodium following intra- 

 muscular injection of labelled sodium chloride(^>. Radio-sodium therefore 

 proves to be an important tool in the study of circulation of body fluids, 

 a process of basic importance. 



FURTHER APPLICATIONS OF RADIO-SODIUM 



The application of radio-sodium as an indicator opens a convenient 

 way to determine the permeability of phase boundaries of different type 

 present in the animal and plant organisms ;(') nevertheless, it has its 

 limitations. (8) Radio-sodium being used as a tracer, the rate was measured 

 at which sodium passes through the placenta from the mother to the 

 offspring, passes from the circulation into the cerebrospinal fluid, pene- 

 trates into the aqueous tumour or through the stomach wall, intrudes 

 into the erythrocytes,^^^. ^^^ is distributed between cytoplasm and nuc- 

 leus, (^) and so on. 



Time does not permit me to describe the interesting experiments of 

 Levi and Ussing,^!") which prove that the two sides of the frog's skin 

 have a distinctly different permeability to sodium. In these experiments 

 the Ringer solution facing the inner surface of the excised frog skin was 



• 



^«^ Elkin, Cooper, Rohreb, Miller and Dennis, Surg. Oynecol. Obstet. 87, 



1 (1948). 

 ('^ Cf. Hevesy, Radioactive Indicators, Interscience Publishers, New York (1948). 

 ^8) UssiNG, Cold Spring Harbor Symp. Quant. Biol. 13, 193 (1948^. 

 ''s^Abelson and Dubvee, Biol. Bull. 96, 205 (1949). 

 ^^'^^ Nature, Lond. 164, 928 (1949). 



