Oiiginally communicated in Kgl. Danske VidensJcabernes Selskab. Biologiske 



MeddeleUer, 16, 8 (1941) 



38. CIRCULATION OF PHOSPHORUS IN THE FROG 



G. Hevesy, L. Hahn and 0. Rebbe 



From the Institute of Theoretical Physics and the Zoophysiological Laboratory, 



University of Copenhagen 



This paper contains the description of some experiments on the circu- 

 lation of phosphorus in the frog using racliophosphorus as an indicator. 

 The experiments described were carried out in the course of the last 

 six years^^). 



EXPERIMENTAL PROCEDURE 



Most of the radioactive phosphorus (^^P) used in these experiments was pre- 

 pared by irradiating carbon disulphide with neutrons emitted by a radium-beryl- 

 Hum source. The ^^p produced was extracted with diluted nitric acid and turned 

 into sodium phosphate. This sodium phosphate of negligible weight (10""io gm 

 or less) was dissolved in 0.6 per cent sodium chloride solution. A few tenths of a 

 cubic centimetre of the solution were injected into the lymph sack of Rana escu- 

 lenta or Rana hungarica. In our earlier experiments, the injection took place 

 at the start of the experiment; in our later work, however, we injected labelled 

 phosphate several times during the experiment in order to keep the activity of 

 the plasma at an approximately constant level. Experiments were carried out 

 both at 0° and at about 20°; their duration varied between 5 minutes and 400 

 hours. The muscle tissue was put into liquid air immediately after its removal 

 and the acid soluble constituents were extracted with cold 10 per cent trichloro- 

 acetic acid. The filtiate obtained was at once added to a solution contaraing ammo- 

 nia and magnesium citrate. By this procedure, all inorganic P present in the tri- 

 chloroacetic extract was precipitated. The next step was to hydrolyse the creatine- 

 phosphoric acid present in the filtrate. In our early work, we decomposed the 

 creatine phosphoric acid by adding anunonium molybdate and keeping the solution 

 for 1 hour at 40° in 1 N. HgSO^. Later, we omitted the addition of ammonium 

 molybdate and split off the phosphate by letting the acidified solution boil for 

 a short time, as proposed by Meyerhof et a/ia.^2)xhe phosphate group, split off 

 from the creatinephosphoric acid, was then precipitated as ammonium magnesium 



^1^ O. Rebhk, M. Sc, who has taken the deepest interest in the problems dis- 

 cussed in this paper and worked for several years almost incessantly on their 

 elucidation suffered an untimely death the 5th of December, 1940. 



^-^ O. Meyerhof, P. Ohlmeher, W. Gentnek and H. Maier -Leibnitz, Biochem. 

 Z. 298, 400 (1938). 



