Active Na-K transport and the rate of ouabain binding. The effect of insulin and other stimuli on skeletal muscle and adipocytes.
1. The effect of stimulation or inhibition of active Na-K transport on [(3)H]ouabain binding has been investigated in isolated soleus muscles and adipocytes.2. In rat soleus muscle, the ouabain-sensitive component of (42)K influx was stimulated by insulin (100 m-u/ml.), adrenaline (6 x 10(-6)M), and by pre-incubation with veratrine (10(-5)M) or in a K-free buffer. In all of these instances, the rate of ouabain binding was increased by 41-113%. Conversely, pre-treatment with tetracaine (0.2 mM) decreased the (42)K-influx and diminished the rate of [(3)H]ouabain binding by 36%.3. Neither insulin, adrenaline or tetracaine produced any detectable change in the total number of ouabain-binding sites (as measured under equilibrium conditions) in rat soleus muscle.4. In mouse and guinea-pig soleus muscle and in fat cells isolated from rats, insulin also increased the rate of [(3)H]ouabain binding without producing any significant change in the total number of ouabain-binding sites.5. Both in soleus muscle and the epididymal fat pad of the rat, there was a linear correlation between (42)K influx and the initial rate of [(3)H]ouabain binding.6. It is concluded that the rate of ouabain binding is determined significantly by the rate of active Na-K transport, but within the time intervals studied (4-6 hr) stimulation or inhibition of the Na pump does not lead to any appreciable change in the total number of Na pumps. It seems unlikely that the stimulation of active Na-K transport by insulin or adrenaline is due to unmasking or de novo synthesis of Na pumps.
D000273:Adipose Tissue / Q000187:drug effects*; D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D001693:Biological Transport, Active / Q000187:drug effects; D004837:Epinephrine / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D051379:Mice; D009132:Muscles / Q000187:drug effects*; D010042:Ouabain / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D013748:Tetracaine / Q000494:pharmacology; D013997:Time Factors; D014702:Veratrine / Q000494:pharmacology
D007328:Insulin; D013748:Tetracaine; D010042:Ouabain; D012964:Sodium; D014702:Veratrine; D011188:Potassium; D004837:Epinephrine