Rudolf Schoenheimer and the concept of the dynamic state of body constituents.

In 1935 Rudolf Schoenheimer (1898-1941) introduced the isotopic tracer technique in metabolic research. The results of his experiments led to a new view of metabolism and nutrition and the evolution of a concept of "continual regeneration," i.e., of continual release and uptake of substances by the cell and, thus, of a "dynamic state of body constituents." This dynamic view of metabolism can be traced back to the thinking of some investigators of the 19th and early 20th century, notably C. Bernard and F. G. Hopkins. It was Schoenheimer, however, who provided clear experimental evidence of the dynamic concept of metabolism.