Alterations in lipid metabolism of developing muscle cells in culture.

Embryonic chick muscle cells in the infused (myoblast) and fused (myotube) states differentially incorporate [3H]palmitic acid into their cellular lipids. Myoblasts incorporated [3H]palmitic acid 6--7-fold greater than myotubes in the triglyceride fraction. The endogenous triglyceride levels, however, were similar for the two developmental stages indicating increased triglyceride turnover in the myoblast compared to that of the myotube. Myotubes showed an increased incorporation of [3H]palmitic acid into sphingomyelin compared to myoblasts. Myoblasts and myotubes had a similar phospholipid composition. The data indicate that fusion is characterized by a decrease in triglyceride turnover possibly reflecting a shift from oxidative to glycolytic metabolism to coincide with the fusion process.