RADIOACTIVE INDICATORS IN BIOCHEMISTRY 



965 



APPLICATION OF SODIUM IN CIRCULATION STUDIES 



Radio-sodium can successfully be applied in the study of the circulation 

 velocity of the body fluids. Although, in experiments described earlier, 

 blood-plasma samples were taken at various intervals and their activities 

 were compared with the activity of a known aliquot of the injected 

 sodium chloride, yet in circulation studies it may be desirable to measure 

 outside the body the rate of propagation of the activity injected. As radio- 



Fig. 2. — Radio-sodium "build-up" curves in a patient with severe 



hypertension reheved by thoracolumbar sympathectomy (Quimby) 



(reproduced, with permission, from Nucleonics, 1947, Dec, p. 1). 



sodium emits not only ^S-rays, but also penetrating y-rays, we can very 

 conveniently measure the time which the injected sodium takes to reach 

 the foot by injecting radio-sodium into the arm vein and placing a Geiger 

 counter on the foot. The average value for the circulation time is found 

 to be 45 seconds, the values varying between 15 and 90 seconds. 



We may also be interested in determining after the injection of radio- 

 sodium into the circulation the time necessary to establish equilibrium 

 between the radio-sodium content of the plasma and that of the extra- 

 cellular fluid. This time, although only a few minutes in the rabbit 

 or guinea pig, is appreciably longer in human subjects; it is very different 

 in normal subjects from that in patients suffering from peripheral vas- 

 cular diseases. Such determinations may thus have diagnostic value. 



QuiMBY^^^ injected radio-sodium into an anticubital vein and, by 

 holding the window of a portable shielded Geiger counter against the 

 sole of the foot, measured the arm-to-foot circulation As long as a uni- 



^^^ Nucleonics., Dec. (1947). 



