Incorporation of C¹⁴ from C¹⁴-labeled sugars into CO₂, nucleic acids and protein by isolated rat diaphragm

¹ Department of Physiology, University of Chicago, Chicago, Illinois

The metabolism by isolated rat diaphragm of the following C¹⁴-labeled sugars was investigated: d-glucose, d-xylose, d-galactose, d-mannose, d-fructose, d-ribose, l-sorbose, l-arabinose and d-arabinose. Three (d-glucose, d-mannose and d-fructose) were oxidized to C¹⁴O₂ in significant amounts. C¹⁴ from only these same three sugars was incorporated into nucleic acids by isolated rat diaphragm. C¹⁴ from d-glucose, d-mannose, d-galactose and d-ribose was incorporated into diaphragm protein. The results provide no clue to the nonenergetic mechanism by which d-glucose, d-mannose, l-sorbose, d-xylose and d-ribose stimulate protein synthesis; they do emphasize the metabolic versatility of muscle.