Changes in intracellular ion activities induced by adrenaline in human and rat skeletal muscle.
To study the stimulating effect of adrenaline (ADR) on active Na+/K+ transport we used double-barrelled ion-sensitive micro-electrodes to measure the activities of extracellular K+ (aKe) and intracellular Na+ (aNai) in isolated preparations of rat soleus muscle, normal human intercostal muscle and in one case of hyperkalemic periodic paralysis (h.p.p.). In these preparations, bath-application of ADR (10(-6) M) resulted in a membrane hyperpolarization and transient decreases aKe and aNai which could be blocked by ouabain (3 x 10(-4) M). In the h.p.p. muscle a continuous rise of aNai induced by elevation of aKe to 5.2 mM could be stopped by ADR. In addition, the intracellular K+ activity (aKi), the free intracellular Ca2+ concentration (pCai) and intracellular pH (pHi) were monitored in rat soleus muscle. During ADR aKi increased, pHi remained constant and intracellular Ca2+ apparently decreased. In conclusion, our data show that ADR primarily stimulates the Na+/K+ pump in mammalian skeletal muscle. This stimulating action is not impaired in the h.p.p. muscle.
Ballanyi
K
K
Institut für Zoologie I, Universität Düsseldorf, Federal Republic of Germany.
Grafe
P
P
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006947:Hyperkalemia / Q000378:metabolism*; D008297:Male; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D010243:Paralysis / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000378:metabolism*
D012964:Sodium; D011188:Potassium; D002118:Calcium; D004837:Epinephrine