Immobilization atrophy and membrane properties in rat skeletal muscle fibres.
Wet mass, resting membrane potential, frequency of miniature end-plate potentials and the concentration of [3H]ouabain-binding sites were studied after 7 days' immobilization of the rat soleus and extensor digitorum longus (EDL) muscles in the shortened or stretched position and after 3 and 7 days of remobilization. We observed that the loss of muscle mass by 37% in the rat soleus immobilized for 7 days in the shortened position is accompanied by a membrane depolarization of about 5 mV, a decrease in frequency of miniature end-plate potentials by 60% and a decrease of [3H]ouabain binding by 25%. Only minor changes were found in stretched soleus and in shortened and stretched EDL. After 3 days of remobilization of stretched soleus the muscle mass, [3H]ouabain binding and miniature end-plate potential frequency recovered to control values but the resting membrane potential continued to decrease. All changes induced by immobilization disappeared on day 7 of remobilization.
Zemková
H
H
Institute of Physiology, Czechoslovak Academy of Sciences, Prague.
Teisinger
J
J
Almon
R R
RR
Vejsada
R
R
Hník
P
P
Vyskocil
F
F
D000818:Animals; D001284:Atrophy; D001665:Binding Sites; D007103:Immobilization; D008297:Male; D008564:Membrane Potentials; D009045:Motor Endplate / Q000502:physiology; D009119:Muscle Contraction; D009132:Muscles / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D010042:Ouabain / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D010042:Ouabain