Beta 2-adrenoceptors mediate the stimulating effect of adrenaline on active electrogenic Na-K-transport in rat soleus muscle.
The relative role of beta 1- and beta 2-adrenoceptors in mediating the stimulating effect of adrenaline on active electrogenic Na-K-transport has been assessed in experiments on rat soleus muscles in vitro and in vivo. 2 In the rat isolated soleus muscle, adrenaline (10(-6) M) increases the resting membrane potential (EM) by 5.8 mV and stimulates 22Na-efflux and ouabain-suppressible 42K-uptake by 91 and 94%, respectively. 3 All of these effects are completely blocked by propranolol (10(-5) M), whereas the beta 1-selective adrenoceptor antagonist, metoprolol, was found to be at least 50 times less potent. 4 The beta 2-adrenoceptor agonist, salbutamol, was at least 100 times as potent as H133/22 (a beta 1-selective agonist) in stimulating 22Na-efflux and 42K-influx. 5 In experiments performed under pentobarbitone anaesthesia, the intravenous injection of adrenaline (5 microgram) or salbutamol (0.5 to 50 microgram) led to a rapid and marked increase in the EM of the exposed soleus muscle. This hyperpolarizing effect could not be accounted for by the concomitant, relatively modest change in extracellular K.
D000420:Albuterol / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D004837:Epinephrine / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D011941:Receptors, Adrenergic / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D012964:Sodium / Q000378:metabolism*; D013997:Time Factors
D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D012964:Sodium; D000420:Albuterol; D011188:Potassium; D004837:Epinephrine