ENZYME-ACTIVITY PATTERNS OF MYOSIN ATPASE, ALPHA-GLYCEROPHOSPHATE DEHYDROGENASE AND SUCCINATE-DEHYDROGENASE WITHIN DIFFERENT MUSCLE-FIBER TYPES

Muscle fibre compositions of five different rabbit muscles were determ ined by combining two enzyme-histochemical reactions (NADH tetracolium oxidoreductase and myosin ATPase after alkaline preincubation). The d ifferentiation into the fibre types, fast twitch glycolytic (FTG), fas t twitch oxidative (FTO), and slow twitch oxidative (STO) was possible by a reliable staining classification. Aim of the study was the estim ation of enzyme activity patterns within the three different fibre typ es. For this purpose, four serial cross-sections with several enzyme h istochemical reactions were performed: alkaline combination method for fibre type determination, the reactions of myosin ATPase, alpha-glyce rophosphate dehydrogenase (GPDH), and succinate dehydrogenase (SDH). T he measurement procedure for the estimation of enzyme activities was b ased on the proportionality between the intensity of the enzyme histoc hemical staining reaction and the degree of enzyme activity. The activ ities of GPDH (indicator for glycolytic metabolism) and SDH (oxidative metabolism) were inverse. The calcium-activated myosin ATPase showed only little activity in slow twitch fibres after alkaline preincubatio n. In contrast to slow twitch fibres, ATPase activity in fast twitch f ibres was relatively high. The results showed that the classification of muscle fibre types due to their myosin ATPase activities and their main metabolisms (oxidative and glycolytic respectively) is justified.