Extraocular muscles: Extraocular muscle metabolism

A defining characteristic of the extraocular muscles is their fast and constant activity. To sustain it, energy demands by the contractile apparatus must be met by energy supply pathways. We have just begun to outline major differences in the relative importance of some pathways, such as the use of lactate for aerobic metabolism, loss of creatine kinase as an ATP buffering system, and the use of mitochondria as calcium sinks. More importantly, there is now concrete evidence demonstrating divergence in mitochondrial composition and function between extraocular and prototypical skeletal muscles. These differences are likely to influence the contractile function of the extraocular muscles and may determine their preferential involvement in some congenital and age-related mitochondrial myopathies.