POTASSir^[ IXTERCIIAXGE IX THE HUMAX BODY 



557 



virine. This result is in accordance with the general experience according 

 to which urine collected between the early hours of the day and noon 

 has the highest potassium concentration. 



Table 3 



Total urine volume = 2.880 cc. 



Percentage of the ^^K administered present in the total urine 



9.1 per cent. 



DISCUSSION 



While the accuracy of the method applied does not suffice to deter- 

 mine whether a full interchange between the potassium of the cells and 

 the potassium of the extracellular fluid took place, the results obtained 

 clearly indicate (see the 2 last columns of Tables 2 and 3) that the greatest 

 part of the labelled potassium ions and, thus, the greatest part of all 

 potassium ions taken with the food find their way within 16 hours or 

 less into the tissue cells while potassium ions formerly located in the 

 cells move simultaneously into the extracellular fluid. In the average 

 urine sample collected during the experiment, the potassium was found 

 to be markedly less active than in the samples collected after the lapse 

 of 15 hours. This is due to a higher activity of the potassium excreted 

 in the first phase of the experiment. This result indicates that the inter- 

 change between cellular and extracellular potassium is not a very rapid 

 process since it takes several hours before a large part of the extracellular 

 potassium interchanges with the potassium of the cells. 



Apparent Volume of Distribution 



In connection with the experiments reported in this note, it is of 

 interest to recall experiments by BouRDiLLOisr (1937) in which the 

 apparent volume of distribution of potassium chloride taken by him 

 by mouth was investigated. The apparent volume of distribution = 



