Effects of Dynamic and Static Loads on the Concentration of Sodium and Potassium in Murine Skeletal Muscles

The effects of dynamic and static load on the intracellular concentrations of sodium (Nai+) and potassium (K⁺_i) in m. soleus and m. biceps, respectively, were studied in mice. Both dynamic (swimming for 60 min) and static (hanging on the grid for 40 min) load led to a 2-fold increase in Nai+ level, a decrease in K⁺_i concentration by 25-35%, and 3-4-fold increase in the Nai+/Ki+ ratio. These effects of dynamic and static loads on the studied parameters remained unchanged in mice subjected to regular physical exercise (swimming or hanging on the grid for 1 h a day over 4 weeks). Our results suggest that dissipation of sodium and potassium transmembrane gradients during physical exercise can be considered as a factor of regulation of functional activity of skeletal muscles, which includes changes in transcription and translation of myokines observed previously.