Article date: April 1980
By: T. CLAUSEN, J.A. FLATMAN in Volume 68, Issue 4, pages 749-755
The relative role of β1‐ and β2‐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.
In the rat isolated soleus muscle, adrenaline (10−6m) increases the resting membrane potential (EM) by 5.8 mV and stimulates 22Na‐efflux and ouabain‐suppressible 42K‐uptake by 91 and 94%, respectively.
All of these effects are completely blocked by propranolol (10−5m), whereas the β1,‐selective adrenoceptor antagonist, metoprolol, was found to be at least 50 times less potent.
The β2‐adrenoceptor agonist, salbutamol, was at least 100 times as potent as H133/22 (a β1‐selective agonist) in stimulating 22Na‐efflux and 42K‐influx.
In experiments performed under pentobarbitone anaesthesia, the intravenous injection of adrenaline (5 μg) or salbutamol (0.5 to 50 μg) 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.
The relative role of β1‐ and β2‐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.
In the rat isolated soleus muscle, adrenaline (10−6m) increases the resting membrane potential (EM) by 5.8 mV and stimulates 22Na‐efflux and ouabain‐suppressible 42K‐uptake by 91 and 94%, respectively.
All of these effects are completely blocked by propranolol (10−5m), whereas the β1,‐selective adrenoceptor antagonist, metoprolol, was found to be at least 50 times less potent.
The β2‐adrenoceptor agonist, salbutamol, was at least 100 times as potent as H133/22 (a β1‐selective agonist) in stimulating 22Na‐efflux and 42K‐influx.
In experiments performed under pentobarbitone anaesthesia, the intravenous injection of adrenaline (5 μg) or salbutamol (0.5 to 50 μg) 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.
DOI: 10.1111/j.1476-5381.1980.tb10868.x
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