Premium
β 2 ‐ADRENOCEPTORS MEDIATE THE STIMULATING EFFECT OF ADRENALINE ON ACTIVE ELECTROGENIC NA‐K‐TRANSPORT IN RAT SOLEUS MUSCLE
Author(s) -
CLAUSEN T.,
FLATMAN J.A.
Publication year - 1980
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1980.tb10868.x
Subject(s) - chemistry , propranolol , soleus muscle , salbutamol , agonist , endocrinology , medicine , metoprolol , ouabain , antagonist , in vivo , efflux , pharmacology , skeletal muscle , receptor , biochemistry , sodium , biology , microbiology and biotechnology , organic chemistry , asthma
1 The relative role of β 1 ‐ and β 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 (E M ) by 5.8 mV and stimulates 22 Na‐efflux and ouabain‐suppressible 42 K‐uptake by 91 and 94%, respectively. 3 All of these effects are completely blocked by propranolol (10 −5 m ), whereas the β 1 ,‐selective adrenoceptor antagonist, metoprolol, was found to be at least 50 times less potent. 4 The β 2 ‐adrenoceptor agonist, salbutamol, was at least 100 times as potent as H133/22 (a β 1 ‐selective agonist) in stimulating 22 Na‐efflux and 42 K‐influx. 5 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 E M of the exposed soleus muscle. This hyperpolarizing effect could not be accounted for by the concomitant, relatively modest change in extracellular K.