Originally published in Z)a«6A(^ V idenskabernes Selskab Biol. Mcrhl. 22. no. 9(I95o) 



24. CONSERVATION OF SKELETAL CALCIUM ATOMS 



THROUGH LIFE 



(1 . Hevesy 



From the Institute for Research in Organic Chemistry, Stockholm 

 Dedicated to Professor Niels Bohr on the occassion of Jiis 70lh birthday 



From the earliest beginning, Professor Niels Bohr has shown great 

 interest in the application of radioactive indicators to the study of 

 the conservation of skeletal atoms through life. This fact has induced 

 the writer to contribute to this volume with a communication of the 

 results obtained in an investigation on the conservation of skeletal 

 calcium atoms in the adult mouse and on the fate of maternal calcium 

 atoms through generations. 



The first application of an artificially radioactive isotope as a tracei- 

 in 1934 was that of ^^p in a study of the problem whether and to what 

 extent the mineral constituents of the skeleton of the adult organism 

 are replaced during lifetime^^' ^' '^' ''\ By using this radioactive indicator 

 it was possible to demonstrate the dynamic nature of the building u]) 

 of bone tissue. It was found that an initial rapid location of the circu- 

 lating labelled phosphate in the mineral constituents of the skeleton 

 is followed by a slower second effect. The first effect was interpre- 

 ted by us to be due to an interchange between the phosphate ions loca- 

 ted in the surface layer of the bone apatite and in the plasma, the second 

 one, however, to the fact that "the bone is destroyed at certain places 

 and rebuilt under incorporation of labelled phosphate at others". Empha- 

 sis was given to the analogy between these phenomena and those obser- 

 ved when, in early experiments, naturally radioactive isotopes were 

 applied as tracers. Paneth*^*\ when shaking solid sulfate with a solution 

 containing labelled lead ions, observed an interchange of lead ions 

 only between the uppermost molecular layer of the solid salt and the 

 dissolved ions. In studies in which the interchange between the atoms 

 of lead metal and the labelled lead ions of a solution, or vice versa, 

 was investigated, the present author and others^'^' ^- '^ found that msbXiy 

 hundreds Of atomic layers of the lead foil were converted into ions, and 

 a corresponding number of ions into atoms, making out the lead foil. 

 Thus, a renewal of the constituents of a metal foil, involving dissolution 

 and reprecipitation due to "local currents", was found to be a much 

 deeper going process than that occurring between solid lead salt and the 



