History of isotopic experiments in Japan

Of the history of isotopic experiments in Japan, the biochemical application was outlined. The use of isotopes was initiated at Institute of Physical and Chemical Research in 1937. They were used primarily as tracers, and their use increased from 1951. 32P was used from the beginning, followed by 14C. After import of isotopes became possible, 3H, 35S, 45Ca, 131I, 59Fe, etc. were used. Isotopes have been used in approximately 1/4 of all reports in biochemistry, and the progress of measuring techniques is expanding the area of application. The report also reviewed the use of 32P, 24Na, 13N, etc. from the cyclotron at Nishina's Laboratory in the 1930s, the author's experiences with RI in the U.S.A. and the situation after import from the U.S.A. (1950). (Chiba, N.)