Role of potassium and chloride channel during non-fatiguing and fatiguing muscular activity in skeletal muscles

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Muscle fatigue is defined as a decreased capacity of muscle to generate force or do work during repetitive stimulation. It is also a protective mechanism that prevents large ATP depletion and increase in cytosolic calcium, two factors known to cause contractile dysfunctions and fiber damage. One major mechanism of fatigue involves a decrease in calcium release resulting in less force generation. This laboratory has extensively studied how changes in membrane excitability can result in less calcium release, and the main focus being on the Katp channel, sodium and potassium ions. We have provided evidence that the Katp channel is crucial in lowering membrane excitability to protect muscle against contractile dysfunctions and fiber damage. Although there is ample evidence for a contribution of sodium, potassium and hydrogen ions to the decrease in force during fatigue, new and exciting studies, from this laboratory and others, have also provided evidence that under some conditions theses same ions can enhance force or delay fatigue.