Originally communioatod ii Arch. int. pharmacodyn . 86, 33 (1951) 



EFFECTS OF DINITRO-CYCLO-PENTILPHENOL ON THE 

 INCORPORATION OF LABELLED ACETATE CARBON (^ C) 



INTO TISSUE FRACTIONS 



M. L. Beeckmans, H. Casier and G. Hevesy 



Institute for Research in Organic Chemistry, University of Stockholm and 

 J. F. Heymans Institute, Department of Pharmacology. University of Ghent 



As found in studies in which labelled acetate (^^(') was used as an indi- 

 cator, acetate is rapidly metabolized in the animal (1) body. While 

 the bulk of the administered acetate carbon is soon exhaled, some is 

 incorporated into tissue fractions. 



Not only does the amount of administered labelled acetate diminisii 

 rapidly with time, but the specific activity of the body acetate dimi- 

 nishes as well. This is due to the constant new formation of endogenous 

 non active acetate, which is, at least in the early phases of the experi- 

 ment, practically inactive. 



As an effect of the diminution of the specific activity of the body 

 acetate, the sensitivity of the radioactive indicator strongly increases 

 with time. One count of acetate ^^C which indicates the presence of 1 

 microgram of acetate or degradation product of acetate, at an early 

 phase of the experiment may indicate the presence of 10 micrograms at a 

 later phase. 



A change in the metabolic rate of acetate or its degradation products 

 reflects itself in a change in their specific activity. Correspondingly a 

 change in the metabolic rate will lead to a change in the ^^C content of 

 tissue fractions and by following these changes we may conclude if 

 and to what extent metabolic changes took place in the organ considered. 

 If the CO2 production is due to metabolic interference slowed down from 

 90 p.c. to 89 p. c, the incorporation of '^K' into tissue fractions may 

 increase from 10 to 11 °'(, thus with as much as 1/10. 



Gould and assoc. (2) in experiments with adult rats, demonstrated 

 the rapid disappearance of the injected labelled acetate carbon through 

 exhalation as C'Og. The cumulative exhalation amounted in 4 hours 

 to 87 % of the amount injected. After the lapse of 30 min about 1/3 

 was still present in organic form in the rat, 1/3 in inorganic form, while 

 1/3 is excreted as COg. The administration of labelled acetate does not 

 interfere with the normal metabolic processes. Acetate is constantly 

 produced and metabolized in the animal organism, the daily production 



