KEXEWAL OF ACID SOLUBLE PHOSPIIOKIS COMPOUNDS I.\ OUGAXS OF RABBIT 383 



the very fast rate of new-formation of adenosintriphosphatc molecules^ 

 since more than 80 per cent of the labile P of the adcnosintriphosphate 

 present in the corpuscles became renewed during the experiments bolli 

 at high and at low temperatures. 



Summary 



Labelled phosphate was administered to rabbits all through the experiments- 

 in order to keep the activity of the inorganic phosphate of the plasma at a constant 

 level. The experiments took 215 min to 50 days. The comparison of the specific 

 activities of the organic P and the cellular inorganic P extracted from the organs 

 leads to the result that in the course of 215 min more than one-half of the acid 

 soluble P compounds present in the mucosa of the small intestine became renewed. 

 Next the intestinal mucosa, the fastest rate of turnover was found to take place 

 in the kidneys, liver and lungs. 



From the various organic acid soluble phosphorus compounds the most readily 

 hydrolysable ones were found to be renewed at the fastest rate. Fractions contain- 

 ing mainly phosphoglycerate were found to be renewed at an appreciable rate 

 as Avell. 



While the rate of formation of labelled acid soluble organic P compounds 

 inside the corpuscles is rapid, the diffusion of labelled phosphate ions from the 

 plasma into the corpuscles is a slow process. In the course of 12 hours, only about 

 1/4 of the P atoms of the acid soluble phosphorus compounds of the corpuscles 

 entered into exchange equilibrium with the P atoms of the plasma phosphate, 

 while most of the molecules of the compounds mentioned above were renewed 

 during this time inside the erythrocytes. The contrast between the rate of inter- 

 penetration of labelled phosphate and that of its incorporation into several of the 

 acid soluble phosphorus compounds inside the cells is also fovmd in the case of 

 the muscles. 



Labelled phosphate was found to penetrate into the brain tissue at an exceed- 

 ngly low rate. 



