THE USE OF ISOTOPICALLY MARKED CARBON IN THE STUDY OF INTERMEDIARY METABOLISM

Abstract

The outstanding additions to knowledge which have modified the points of view from which problems of metabolism must be approached are summarized. CO2 may no longer be considered as simply an end-product of metabolism but must be thought of as an essential compound in certain metabolic reactions in higher as well as lower forms of life. Compounds, such as lactic acid, are not only specific precursors of more complex compounds but also contributors to the metabolic pool from which the complex compounds are formed. More intimate information is now available on the reactions relating carbohydrate, fat and protein precursors and their contribution to the metabolic pool of each. When these tools which permit the tracing Of atoms in the body come into more general use, many of the earlier conclusions regarding the fate of substances will doubtless require drastic revision, and many problems which hitherto could not be approached will become vulnerable to attack.