Enzyme activities, histochemistry and myosin light chain pattern in extraocular muscles of rabbit

A study was performed on enzyme activities, myosin light chain pattern and histochemical composition of extraocular muscles (EOM) of rabbit. The results were compared with those from slow-twitch soleus and fast-twitch psoas limb muscles. EOM were found to contain myosin light chains of both slow and fast skeletal muscles, with the latter being predominant. The activities of the enzymes regulating glycolysis and lactic acid fermentation were found to lie between those measured in soleus and psoas muscles, whereas the activities of the enzymes involved in oxidative metabolism were found to be very similar or even higher than in soleus muscle. All five isozymes of lactate dehydrogenase (LDH 1-5) were found in EOM. The predominant species was LDH-3 illustrating that this pattern is uncharacteristic of either slow soleus or fast psoas muscles. The complex structural and functional characteristics of EOM might result from the observed heterogeneity of fibres.