The reversible binding of glycolytic enzymes in ovine skeletal muscle in response to tetanic stimulation

The extent of binding of glycolytic enzymes to the particulate fraction of homogenates was measured in sheep hind muscles after electrical stimulation. As compared to the control muscles, stimulation led to significant increases in the amount of phosphofructokinase, aldolase and glyceraldehyde-3-phosphate dehydrogenase bound to the particulate fraction. The bindng of other glycolytic enzymes was not significantly altered. A servey of different hind limb muscles at variable rates of stimulation revealed that each muscle exhibited its own characteristic response pattern in terms of the level of increased enzyme binding. Generally, an increased stimulation rate led to greater enzyme adsorption. The increase in enzyme binding was rapidly reversible for it was shown that the amount of enzyme bound quickly returned to control values when the muscles were allowed to recover in the live anaesthetised animal following cessation of stimulation. Those muscles which exhibited increased enzyme binding were characterised by a marked loss of glycogen and accumulation of lactate suggesting that accelerated glycolytic flux was a necessary condition for the observation of increased enzyme binding. In support of this, enzyme adsorption was observed to be greatest on stimulation of ischemic muscles, whereas in trained muscles, or muscles with depleted glycogen stores induced by prior adrenalin treatment, the increased enzyme binding response was greatly diminished. It is concluded that the variable binding of key glycolytic enzymes has a role to play in the regulation of glycolytic behaviour in skeletal muscle.