Muscle action potential propagation velocity changes during activity

Fatigue from high frequency stimulation is associated with EMG signal changes, which are primarily due to a slowing of the sarcolemma conduction velocity. In the present study, in which isolated mouse soleus and extensor digitorum longus muscles have been studied, it is shown that the action potential propagation velocity is (1) decreased by an increased extracellular potassium concentration, (2) independent of extracellular pH, (3) decreased by low intracellular pH, and (4) nearly independent of moderate changes in the sodium gradient. The EDL muscle is more affected than the soleus muscle. The ion effects on propagation velocity are seen within the physiological ranges. The propagation velocity was decreased after 2 min of electrical stimulation and recovered with a time course similar to the pH recovery. The effects of extracellular potassium and internal pH are due to independent mechanisms.

[1]  W. Moore,et al.  The role of protons in nerve conduction , 1973 .

[2]  C. J. Luca.  Myoelectrical manifestations of localized muscular fatigue in humans. , 1984 .

[3]  R. Fitts,et al.  Fatigue from high- and low-frequency muscle stimulation: Role of sarcolemma action potentials , 1986, Experimental Neurology.

[4]  C. Juel.  Intracellular pH recovery and lactate efflux in mouse soleus muscles stimulated in vitro: the involvement of sodium/proton exchange and a lactate carrier. , 1988, Acta physiologica Scandinavica.

[5]  G. W. Mainwood,et al.  The effect of acid-base balance on fatigue of skeletal muscle. , 1985, Canadian journal of physiology and pharmacology.

[6]  B. Bigland-ritchie,et al.  Conduction velocity and EMG power spectrum changes in fatigue of sustained maximal efforts. , 1981, Journal of applied physiology: respiratory, environmental and exercise physiology.

[7]  K. Mills,et al.  Muscle fatigue in myophosphorylase deficiency: power spectral analysis of the electromyogram. , 1984, Electroencephalography and clinical neurophysiology.

[8]  K. W. Snowdowne.  Subcontracture depolarizations increase sarcoplasmic ionized calcium in frog skeletal muscle. , 1985, The American journal of physiology.

[9]  B. Bigland-ritchie,et al.  Excitation frequency and muscle fatigue: Mechanical responses during voluntary and stimulated contractions , 1979, Experimental Neurology.

[10]  I Petersén,et al.  Conduction velocity in ischemic muscle: effect on EMG frequency spectrum. , 1970, The American journal of physiology.

[11]  H. Kwiecinski,et al.  Membrane currents in human intercostal muscle at varied extracellular potassium , 1984, Muscle & nerve.

[12]  R. Zucker.  Excitability changes in crayfish motor neurone terminals , 1974, The Journal of physiology.

[13]  R. Malenka,et al.  Effects of extracellular potassium concentration on the excitability of the parallel fibres of the rat cerebellum. , 1983, The Journal of physiology.

[14]  H. Atwood,et al.  Membrane properties and contraction of single muscle fibers in the mouse. , 1972, The American journal of physiology.

[15]  S G Waxman,et al.  Modulation of parallel fiber excitability by postsynaptically mediated changes in extracellular potassium. , 1981, Science.

[16]  B. S. Pallotta.  Calcium‐activated potassium channels in rat muscle inactivate from a short‐duration open state. , 1985, The Journal of physiology.

[17]  R. Edwards.  New techniques for studying human muscle function, metabolism, and fatigue , 1984, Muscle & nerve.