Metabolic types of muscle in the sheep: II. Lactate dehydrogenase activity and LDH isoenzyme distribution.

Lactate dehydrogenase activity and isoenzyme distribution were measured in fast-twitch red, slow-twitch red and fast-twitch white muscles in the sheep. Total enzyme activity is higher in fast-twitch muscles irrespective of their colour type. Isoenzymes M4 and H4 bear an inverse relationship, M4 being predominant in fast-twitch red and white muscles, and H4 in heart muscle and slow-twitch red muscles.