Pharmacological and molecular characterisation of beta-adrenoceptors in adult rat diaphragm muscle.
Using pharmacological and molecular approaches to investigate beta-adrenoceptor (beta-AR) subtype expression in adult rat diaphragm, we found that adenylyl cyclase (AC) was potently stimulated by the beta2-AR-selective agonist fenoterol, weakly stimulated by the beta1-AR-selective agonist prenalterol and unaffected by the beta3-AR agonist CGP12177. AC activity in response to a submaximal isoproterenol concentration was potently inhibited by the beta2-AR-selective antagonist ICI118551, whereas the beta1-AR-selective antagonist CGP20712A was effective only in very high concentrations. (-)-[125I]-cyanopindolol ([125I]-CYP) saturation binding experiments indicated a single affinity component (dissociation constant (Kd) = 22 +/- 2 pM) for beta-AR sites (maximal beta -AR density (Bmax) = 14 +/- 2 fmol/ mg). Eadie-Hofstee analysis of [125I]-CYP displacement curves by beta1-, beta2- or beta3-AR-selective ligands allowed to characterise a homogeneous population of beta2-AR sites. Finally, reverse transcriptase-polymerase chain reaction analysis of beta-AR subtype mRNAs identified beta2-AR transcripts but no beta1- and beta3-AR mRNAs. Our results demonstrate that beta2-AR is the only beta-AR subtype expressed in the diaphragm.
Collet
F
F
Institut National de la Santé et de la Recherche Médicale, Unité 296, Faculté de Médecine Hôpital Henri Mondor, Créteil, France. secr.u492@im3.inserm.fr
Féve
B
B
Frisdal
E
E
Pavoine
C
C
Pecker
F
F
Atlan
G
G
D000262:Adenylyl Cyclases / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000375:Aging / Q000378:metabolism; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005280:Fenoterol / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011294:Prenalterol / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*; D018342:Receptors, Adrenergic, beta-1 / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism; D022702:Receptors, Adrenergic, beta-3
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D007093:Imidazoles; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D022702:Receptors, Adrenergic, beta-3; D005280:Fenoterol; C026777:ICI 118551; C047975:cyanopindolol; D010869:Pindolol; C049763:CGP 20712A; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D011294:Prenalterol; C033394:CGP 12177