The Journal of general physiologyJul 7, 2022

Specific enzymes control separate use of stored energy in rat muscles

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Updated Apr 3, 2026

Abstract

Three distinct glycogen pools in skeletal muscle are associated with the energy needs of specific ATPases.

Glycogen is vital for energy production in skeletal muscle fibers.
Transmission electron microscopy has revealed a heterogeneous distribution of glycogen pools within skeletal muscle.
Different ATPases (Ca2+, Na+,K+, and myosin) utilize specific local glycogen pools.
Findings indicate that glycogen metabolism is compartmentalized, with separate pools supporting distinct energy-requiring processes.
This model may enhance understanding of muscle fatigue and metabolic disorders.

Simplified

Glycogen is a key energy substrate in excitable tissue, including in skeletal muscle fibers where it also contributes to local energy production. Transmission electron microscopy imaging has revealed the existence of a heterogenic subcellular distribution of three distinct glycogen pools in skeletal muscle, which are thought to reflect the requirements for local energy stores at the subcellular level. Here, we show that the three main energy-consuming ATPases in skeletal muscles (Ca2+, Na+,K+, and myosin ATPases) utilize different local pools of glycogen. These results clearly demonstrate compartmentalized glycogen metabolism and emphasize that spatially distinct pools of glycogen particles act as energy substrate for separated energy requiring processes, suggesting a new model for understanding glycogen metabolism in working muscles, muscle fatigue, and metabolic disorders. These observations suggest that the distinct glycogen pools can regulate the functional state of mammalian muscle cells and have important implications for the understanding of how the balance between ATP utilization and ATP production is regulated at the cellular level in general and in skeletal muscle fibers in particular.

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Specific enzymes control separate use of stored energy in rat muscles

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