beta-Adrenergic effect on Na+-K+ transport in rat skeletal muscle.
1. Intact rat extensor digitorum longus muscles soaked in L-isoproterenol plus 10(-5) M ouabain gained less sarcoplasmic Na+ than did muscles soaked in ouabain alone. Half maximal effect was produced by 10(-8) M L-isoproterenol. 2. D-Isoproterenol and oxidized L-isoproterenol were only 3 and 1%, respectively, as potent as L-isoproterenol. Other catechols tested had no effect. 3. The effect of L-isoproterenol on sarcoplasmic Na+ content appears to be a beta-adrenergic function in that it was blocked by propranolol, but not by phentolamine, and could be mimicked by dibutyryl cyclic AMP or by caffeine. 4. Reduced gain in sarcoplasmic Na+ was accompanied by reduced loss of sarcoplasmic K+. 5. L-Isoproterenol increased loss of sarcoplasmic Na+ in the absence of ouabain, in muscles recovering from cold treatment. 6. Results suggest that the beta-adrenergic system stimulates a coupled Na-K+ pump. 7. A model is proposed in which stimulation of the Na+-K+ pump in response to beta-adrenergic agents involves a number of intermediate steps, identified tentatively.
D000818:Animals; D001693:Biological Transport, Active; D003994:Bucladesine / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D002396:Catechols / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology*; D007700:Kinetics; D007980:Levodopa / Q000494:pharmacology; D008297:Male; D008954:Models, Biological; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D010084:Oxidation-Reduction; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000378:metabolism*
D002396:Catechols; D002110:Caffeine; D007980:Levodopa; D010042:Ouabain; D003994:Bucladesine; D012964:Sodium; D007545:Isoproterenol; D011188:Potassium