Growth-related changes in the intracellular distribution of succinate dehydrogenase activity in turkey muscle

The intracellular distribution of succinate dehydrogenase (SDH) activity was measured and mapped in iliotibialis cranialis muscle fibers of growing turkeys. Two weeks after hatching, fibers with strong myofibrillar adenosine triphosphatase (ATPase) were larger in cross sectional area than fibers with weak ATPase, but fibers with weak ATPase subsequently exhibited more rapid relative growth. At two weeks, both types of fibers had stronger SDH activity in their central axis than in the subsarcolemmal region. At ten weeks this gradient was reversed so that SDH activity declined from the periphery to the axis (a negative centripetal gradient of SDH activity). Fibers with strong ATPase developed the steepest negative gradients of SDH activity. Fibers with weak ATPase tended to have more uniformly distributed SDH activity, even when fibers had grown quite large.