The ability of isolated fresh bone fragments to remain metabolically active for long periods in fully defined simple media has been well documented in this and other laboratories (I-3). The isolated tissue uses oxygen and incorporates 14C from labeled glucose briskly into lactate, C@ S, and bone matrix (1, 4). More recently, the inclusion of labeled amino acids in the medium has shown that the fragments also retain the ability to synthesize collagen, although supplied with only one esogenous amino acid (5). The remaining amino acids necessary for collagen synthesis under these conditions were assumed to derive from the tissue breakdown which accompanies such incubations in vitro. The absence of an effect on the incorporation of labeled proline into collagen when glucose was removed from the medium (5) suggested that glucose was not an important source of collagen amino acids.

Preliminary experiments with uniformly labeled glucose-14C as a tracer, however, revealed that a significant amount of glucose carbon appeared in the alkali-insoluble collagen of the bone matrix. This communication presents a more detailed study of the pathway of glucose metabolism within the bone slice utilizing the distribution of label from exogenous uniformly labeled glucose-14C.