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Rubidium influx into rat skeletal muscles in relation to electrical activity
Author(s) -
Kernan R. P.,
McDermott Mary
Publication year - 1973
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1973.sp010312
Subject(s) - chemistry , tenotomy , depolarization , fast twitch muscle , soleus muscle , medicine , tonic (physiology) , denervation , rubidium , endocrinology , anatomy , skeletal muscle , biology , tendon , potassium , organic chemistry
1. Rates of 86 Rb influx were compared in vivo over 2, 4 and 6 hr periods in various tonic and phasic muscles of rat following its I.P. injection. During the 2 hr period its influx rate into soleus was about 4 times that of the vastus with the EDL muscles at an intermediate rate. Uptake by diaphragm was fastest reaching equilibrium within 2 hr. 2. Unilateral section of the sciatic nerve 48 hr before 86 Rb injection reduced isotope uptake into soleus to about 50% of its contralateral control muscle over a 4 hr period. In EDL muscles on the other hand nerve section increased influx by about 75% of control in conscious rats and more than doubled influx in anaesthetized rats. 3. Tenotomy of soleus reduced 86 Rb influx to 40% of control, but tenotomy in EDL was without effect in influx. 4. Uptake of urea into muscles within 5 min of its I.V. injection was used to determine the possibility of muscle blood flow determining 86 Rb influx. Accumulation of urea was not significantly different in control and denervated EDL muscles nor between soleus and vastus muscles in anaesthetized rats, so it seems unlikely that blood flow is important here. 5. Membrane depolarization in response to addition of 30 m M rubidium to external bathing fluid was greater in the case of denervated than in control EDL muscles which was in keeping with the greater 86 Rb influx seen in the former muscles. The ouabain sensitivity of rubidium‐induced depolarization in the denervated EDL muscles would suggest, however, that rubidium enters the fibres actively.