[Relation between myoglobin levels and succinate dehydrogenase activity in muscle fibers]

We compared the histochemical activity of succinate dehydrogenase (SDH) and the intensity of reaction to the presence of myoglobin (Mb) in the same muscle fibres m. longissimus thoracis (MLT), m. semimembranosus (MSM), m. rectus femoris (MRF) and caput longum m. tricipitis brachii (MTB). At the same time we also ascertained the myoglobin content of one gram of fresh muscle. We found that the muscle fibre in all the muscles studied in which there is the most intensive reaction in the test for SDH are also the most intensively coloured in the test for Mb. There is also the same relationship in intermediary and white fibres. The reaction in testing for SDH on a cross section is greatest in the subsarcolemmic area. Similar tendencies appear in the distribution of Mb, although they are less marked and only in fibres with intensive reaction. Different muscles have different myoglobin levels. Muscles with a higher proportion of red and intermediary fibres contain more myoglobin than muscles with a high proportion of white fibres. The quantitative values of the levels of Mb (g/fresh muscle) are not, however, proportional to the share of individual types of muscle fibres in the muscles studied.