Effects of insulin and epinephrine on Na+-K+ and glucose transport in soleus muscle.
To identify possible cause-effect relationships between changes in active Na+-K+ transport, resting membrane potential, and glucose transport, the effects of insulin and epinephrine were compared in rat soleus muscle. Epinephrine, which produced twice as large a hyperpolarization as insulin, induced only a modest increase in sugar transport. Ouabain, at a concentration (10(-3) M) sufficient to block active Na+-K+ transport and the hyperpolarization induced by the two hormones, did not interfere with sugar transport stimulation. After Na+ loading in K+-free buffer, the return to K+-containing standard buffer caused marked stimulation of active Na+-K+ transport, twice the hyperpolarization produced by insulin but no change in sugar transport. The insulin-induced activation of the Na+-K+ pump leads to decreased intracellular Na+ concentration and hyperpolarization, but none of these events can account for the concomitant activation of the glucose transport system. The stimulating effect of insulin on active Na+-K+ transport was not suppressed by amiloride, indicating that in intact skeletal muscle it is not elicited by a primary increase in Na+ influx via the Na+/H+-exchange system.
D019325:3-O-Methylglucose; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002034:Bumetanide / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008757:Methylglucosides / Q000378:metabolism*; D008759:Methylglycosides / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D007328:Insulin; D008757:Methylglucosides; D008759:Methylglycosides; D009004:Monosaccharide Transport Proteins; D002034:Bumetanide; D019325:3-O-Methylglucose; D010042:Ouabain; D000584:Amiloride; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; D004837:Epinephrine