Scaling of cytoplasmic and mitochondrial enzymes and proteins in skeletal muscle of a catfish

  The skeletal muscle has an effective chemical–mechanical transducer system to generate physical forces which needs a constant supply of Adenosine triphosphate (ATP). The ATP requirement may vary with the body size of organisms. Studies of the size‐dependent properties of animals have been mainly focused on aerobic processes and the underlying structures supporting them (S chmidt ‐N ielsen 1984; E wart et al. 1988; B errioslopez et al. 1996). Some attempts have been made to correlate anaerobic process with body mass in fish (S omero and C hildress 1980, 1990). It has been reported that anaerobic metabolic processes exhibit different scaling patterns to those of aerobic processes (S ullivan and S omero 1980; H eusner 1987; H ochachka et al. 1987; S omero and C hildress 1990). The differences between aerobic and anaerobic capacities may be due to the differing roles of inter‐organ interactions in general metabolism. The scaling of metabolic enzymes has also been shown to be associated with the scaling of protein concentrations in fish (S omero and C hildress 1990). M c M ahan (1984) has remarked that the scaling of aerobic metabolism cannot be explained by engineering principles involving skeletal muscle strength. Thus in spite of some strong experimental supports, it has been too difficult to explain the intricacy of aerobic scaling (S chmidt ‐N ielsen 1984; C alder 1987; H eusner 1987; S omero and C hildress 1990).W eihs and W ebb (1983) have argued that swimming speed should scale with body size to favour prey capture. Further, B errioslopez et al. (1996) demonstrated the scaling of skeletal mass to body mass in fish. Since Clarias batrachus is a predatory teleost, the scaling of aerobic (MDH) and anaerobic (LDH) enzymes and proteins have been studied to test the existing hypotheses about the functional roles of metabolic scaling in fish.