Rapid up‐ and down‐regulation of hexokinase II in rat skeletal muscle in response to altered contractile activity

An up to 14-fold increase in total hexokinase activity induced by low-frequency stimulation in rat fast-twitch muscle was followed by a rapid decay in enzyme activity after cessation of stimulation. In vivo labeling revealed that these alterations were related to rapid changes in [35S]methionine incorporation into hexokinase II. A recovery period of 15 h after cessation of stimulation was sufficient to normalize the approximately 30-fold elevated [35S]methionine incorporation.