RENEWAL OF ACID SOLUBLE PHOSPHORUS COMPOUNDS IN ORGANS OF RABBIT 377 



some extent, due to an extremely low activity of the average inorganic- 

 P of the brain. It is a puzzling result that the total activity found in 

 the brain tissue, due to the presence of active inorganic and organic P, 

 is smaller than that we should expect to find in the interspaces of the 

 brain alone when assuming a proportional distribution of the active 

 inorganic P between the plasma and the extracellular space of the brain 

 tissue. In this calculation, the extracellular space is taken to be 30 per 

 cent of the weight of the brain, as found from the distribution figures, 

 of chlorine and sodium^^) between the plasma and the brain tissue. Our 

 results suggest the assumption that the labelled phosphate ions penetrate 

 at a very slow rate through the capillaries of the brain or, alternatively,, 

 that the figures obtained by determining the distribution of chlorine 

 of sodium between the plasma and the brain do not represent the proper 

 extracellular space of the brain. It is for these reasons that we did not 

 state in Table 1 any figures for the rate of renewal of the acid soluble 

 P compounds present in the brain. 



Table 2 contains data on the activity of different organic P fractions 

 extracted from the kidneys and the liver. The phosphate obtained after 

 7 min hydrolysis contains, as well-known, besides P split off from 

 ereatinephosphoric acid, the labile P of the adenosintriphosphate mole- 

 cules. That the adenosintriphosphate molecules present in the muscle 

 are reorganised at a fast rate was found in our previous experiments^^) 

 Meyerhof and his collaborators^^^ studied the rate of reorganistion of 

 the adenosintriphosphate molecule with incorporation of active inorganic 

 P in experiments in vitro and found this process to take place at a very 

 fast rate. Data on the activity of the phosphorus obtained by hydro- 

 lysing the organic acid soluble phosphorus extracted from perfused 

 cat liver for 7 min are given by Lundsgaard^*\ 



Our experiments lead to the result that at least 76 per cent of the 

 7 min product extracted from the liver of the rabbit became renewed 

 in the course of 215 min. In Lundsgaard's perfusion experiment, the 

 specific activity of the 7 min fraction was found, after 90 min, to amount 

 to 60 per cent of that of the inorganic P extracted from the plasma at 

 the end of the experiment. 



As seen in Tables 2—7 the more readily hydrolysable compound is 

 renewed at a faster rate than the less readily hydrolysable one. That 

 even those compounds which resist treatment with 1 N HgSO^ at 100° 

 for 12 hours or more are renewed, however, at a very appreciable rate 



<i>J. F. Manery and B. Hastings, J. Biol. Chem. 127, 657 (1939). 

 (2) G. Hevesy and O. Rebbe, Nature 141, 1097 (1938); G. B-EVESY, Enzymologia 

 5,138(1938). 



<') O. Meyerhof, P. Ohlmeyer, W. Gentner and H. Maieb-Leibnitz, Biochem. 

 Z. 298, 398 (1938). 



We. Lundsgaabd, Skand. Arch. /. Physiol. 80, 291 (1938). 



