Short Communication An Improved Technique for the Demonstration of Glycogen Depleted Skeletal Muscle Fibres

In 1968, Kugelberg and Edstr6m described a histochemical method to localize skeletal muscle fibres belonging to a single motor unit by depletion of their glycogen. The authors concluded that "contractions produced striking changes in the phosphorylase activity and glycogen content, which varied in different types of fibres". Thus, the pattern of histochemically demonstrated activity of phosphorylase and the glycogen content in tissue sections depends on the "functional state" of the muscle at the moment of sacrifice. Several authors used the method of Kugelberg and Edstr6m (1968), in which the Periodic Acid Schiff (PAS) reaction served to localize the muscle fibres belonging to one motor unit, after repetitive stimulation, in their investigations of physiological characteristics of single motor units. However, the contrast between depleted and non-depleted fibres is often not sufficient for reliable registration. Pre-incubation during 11/2 to 3 h for 0~-glucanuridine-diphosphate-glucosyl-transferase CUDPG-transferase) increased the contrast between both groups of fibres with the PAS reaction (Pool et al. 1978). The same year that Kugelberg and Edstr6m published their work on the characteristics of motor units and pointed to the strong relation between muscle glycogen and histochemically detectable phosphorylase activity, Meijer (1968a, b) described a method in which dextrans were used as a glucosyl acceptor for the demonstration of phosphorylase activity in infarcted, i.e. glycogen depleted, heart muscle. The author recommended the