Homogeneity of [3H]ouabain-binding sites in rat soleus muscle.
Homogeneity or heterogeneity of rat soleus-muscle Na,K-ATPase (Na+ + K+-dependent ATPase) with respect to affinity for [3H]ouabain was evaluated. Since the standard method for measuring specific [3H]ouabain binding to rat skeletal-muscle samples includes subtraction of a value for non-specific [3H]ouabain uptake and retention, and a wash-out in the cold to remove [3H]ouabain from the extracellular phase, it was possible that these procedures could hide a class of [3H]ouabain-binding sites either with low affinity or with a rapid dissociation of [3H]ouabain. However, measurements of [3H]ouabain uptake and retention over the range 0.1-5 mM, as well as the omission of wash-out, gave no evidence for heterogeneity of [3H]ouabain-binding sites in rat soleus muscle. Furthermore, the observation of agreement between the uptake and retention of non-specific [3H]ouabain and of [14C]sucrose gave no evidence for the existence of a major pool of [3H]ouabain-binding sites with low affinity for [3H]ouabain. Assuming homogeneity, the total concentration of [3H]ouabain binding sites in soleus-muscle samples from 12-week-old rats is 278-359 pmol/g wet wt.
Kjeldsen
K
K
Institute of Physiology, University of Aarhus, Denmark.
D000818:Animals; D001665:Binding Sites; D005260:Female; D066298:In Vitro Techniques; D009132:Muscles / Q000378:metabolism*; D010042:Ouabain / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013395:Sucrose / Q000378:metabolism
D013395:Sucrose; D010042:Ouabain