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Active transport of sodium and potassium in mammalian skeletal muscle and its modification by nerve and by cholinergic and adrenergic agents
Author(s) -
Dockry Margaret,
Kernan R. P.,
Tangney Aileen
Publication year - 1966
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.1966.sp008028
Subject(s) - chemistry , isoprenaline , sodium , acetylcholine , decamethonium , denervation , biophysics , potassium , cholinergic , medicine , endocrinology , biochemistry , stimulation , receptor , organic chemistry , biology
1. Active transport of Na + and K + by Na‐rich extensor digitorum and soleus muscles of rat was found to be increased considerably when muscles were innervated during enrichment with Na + in K‐free modified Krebs solution containing 160 m M ‐Na at 2° C and recovery in a similar fluid with 10 m M ‐K and 137 m M ‐Na at 37° C, bubbled with oxygen. 2. Addition of acetylcholine (2·0 μg/ml.) to recovery fluid containing denervated extensors increased active transport, whereas addition of eserine (50 μg/ml.), decamethonium (0·1 μg/ml.) and to a lesser extent tubocurarine (0·26 μg/ml.) inhibited active transport. Blocking of nerve conduction in innervated extensor inhibited K + uptake more than Na + excretion. 3. The membrane potential of Na‐rich extensor muscles measured soon after re‐immersion in recovery fluid was higher in denervated than in innervated muscles. In the latter it was close to the K‐equilibrium potential ( E K ). It is suggested that denervation here makes the Na‐pump electrogenic by decreasing K + uptake either by decreased permeability or by inactivating a K‐pump. Evidence is presented that the latter is more likely. 4. Addition of isoprenaline to Na‐rich soleus muscles in recovery fluid increased active transport and reduced the membrane potential measured soon after re‐immersion in recovery fluid. The Na‐pump still remained electrogenic in the presence of isoprenaline. It was suggested that isoprenaline might also stimulate the Na‐pump, perhaps through activation of lactic dehydrogenase.