Identification and characterisation of beta-adrenoceptors in guinea-pig skeletal muscle.
(-)-[125I]Iodocyanopindolol (ICYP) was used to characterise beta-adrenoceptors in skeletal muscle of the guinea-pig. The binding if ICYP to soleus and gastrocnemius muscles was saturable and reversible with KD values of 10.7 +/- 1.1 and 11.6 +/- 1.4 pM and Bmax values of 84.0 +/- 5.7 and 59.9 +/- 8.6 fmol/mg protein for gastrocnemius and soleus muscles respectively. Hofstee plots for the selective beta 1-adrenoceptor antagonists atenolol and metoprolol and for the selective beta 2-adrenoceptor antagonist ICI 118551 were linear in both skeletal muscles suggesting the presence of homogenous populations of beta-adrenoceptors. Furthermore, from the Ki values for atenolol (8381 +/- 2063 nM), metoprolol (585 +/- 80 nM) and ICI 118551 (0.39 +/- 0.05 nM) in gastrocnemius and ICI 118551 (0.47 +/- 0.09 nM) in soleus muscle, it is concluded that the beta-adrenoceptors in skeletal muscle of the guinea-pig are predominantly if not exclusively of the beta 2-subtype.
Elfellah
M S
MS
Department of Materia Medica, Stobhill General Hospital, Glasgow, U.K.
Reid
J L
JL
D000818:Animals; D006168:Guinea Pigs; D066298:In Vitro Techniques; D020120:Iodocyanopindolol; D007700:Kinetics; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010869:Pindolol / Q000031:analogs & derivatives / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000302:isolation & purification*
D011943:Receptors, Adrenergic, beta; D020120:Iodocyanopindolol; D010869:Pindolol