Breakdown of Small and Large Glycogen Stores in Working Rat Muscles

Contractions caused significant reductions in both pro- and macroglycogen in all glycogen groups and muscle types.

• Both proglycogen and macroglycogen are present in skeletal muscle and contribute to glycogen breakdown during muscle contractions.
• In muscles with higher glycogen levels, macroglycogen is utilized more relative to proglycogen.
• In muscles with normal to low glycogen content, proglycogen is more abundant and contributes more to glycogen breakdown in absolute terms.
• Availability of macroglycogen may facilitate a higher glycogenolytic rate during muscle activity.
• The findings suggest that the total muscle glycogen content influences the rate of glycogen breakdown.

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