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MITOCHONDRIAL OXIDATIVE ENZYME ACTIVITY IN INDIVIDUAL FIBRE TYPES IN HYPO‐ AND HYPERTHYROID RAT SKELETAL MUSCLES
Author(s) -
Johnson M. A.,
Turnbull D. M.
Publication year - 1984
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1984.sp002804
Subject(s) - succinate dehydrogenase , oxidative phosphorylation , dehydrogenase , endocrinology , medicine , enzyme , oxidative enzyme , soleus muscle , mitochondrion , skeletal muscle , chemistry , enzyme assay , citrate synthase , hormone , biochemistry , biology
Quantitative cytochemical and biochemical techniques have been used in combination to study the response of mitochondrial oxidative enzymes in individual muscle fibre types to hypo‐ and hyperthyroidism. Hypothyroidism resulted in decreased activity of succinate dehydrogenase (SDH), L‐glycerol‐3‐phosphate dehydrogenase (L‐GPDH), and D‐3‐hydroxybutyrate dehydro‐genase (D‐HBDH) in all fibre types of both slow‐twitch soleus and fast‐twitch extensor digitorum longus (e.d.l.) muscles. In hyperthyroidism, only L‐GPDH activity increased in e.d.l. but more marked increases were seen in soleus muscles, which also showed increased SDH activity. In addition to these alterations in the enzyme activity in individual fibre types the metabolic profile of the muscle is further modified by the hormone‐induced interconversion of slow‐ to fast‐twitch fibres and vice versa.