title: Membrane Potential Controls the Efficacy of Catecholamine-induced β1-Adrenoceptor Activity.
abstract: G protein-coupled receptors (GPCRs) are membrane-located proteins and, therefore, are exposed to changes in membrane potential (V(M)) in excitable tissues. These changes have been shown to alter receptor activation of certain Gi-and Gq-coupled GPCRs. By means of a combination of whole-cell patch-clamp and Förster resonance energy transfer (FRET) in single cells, we demonstrate that the activation of the Gs-coupled β1-adrenoreceptor (β1-AR) by the catecholamines isoprenaline (Iso) and adrenaline (Adr) is regulated by V(M). This voltage-dependence is also transmitted to G protein and arrestin 3 signaling. Voltage-dependence of β2-AR activation, however, was weak compared with β1-AR voltage-dependence. Drug efficacy is a major target of β1-AR voltage-dependence as depolarization attenuated receptor activation, even under saturating concentrations of agonists, with significantly faster kinetics than the deactivation upon agonist withdrawal. Also the efficacy of the endogenous full agonist adrenaline was reduced by depolarization. This is a unique finding since reports of natural full agonists at other voltage-dependent GPCRs only show alterations in affinity during depolarization. Based on a Boltzmann function fit to the relationship of V(M) and receptor-arrestin 3 interaction we determined the voltage-dependence with highest sensitivity in the physiological range of membrane potential. Our data suggest that under physiological conditions voltage regulates the activity of agonist-occupied β1-adrenoceptors on a very fast time scale.
authors.affiliation: Institute of Pharmacology and Clinical Pharmacy, Biochemical Pharmacological Center Marburg, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany and.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Birk
authors.affiliation: Institute of Physiology, Ruhr-University Bochum, Universitätsstr. 150, 44801 Bochum, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Rinne
authors.affiliation: Institute of Pharmacology and Clinical Pharmacy, Biochemical Pharmacological Center Marburg, Philipps-University Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany and. Electronic address: moritz.buenemann@staff.uni-marburg.de.
authors.forename: Moritz
authors.initials: M
authors.lastname: Bünemann
mesh_terms: D058665:Adrenergic beta-1 Receptor Agonists / Q000494:pharmacology; D019390:Arrestins / Q000378:metabolism; D002395:Catecholamines / Q000494:pharmacology*; D004837:Epinephrine / Q000494:pharmacology; D031541:Fluorescence Resonance Energy Transfer; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D018342:Receptors, Adrenergic, beta-1 / Q000378:metabolism*; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism; D015398:Signal Transduction; D059010:Single-Cell Analysis
chemical_list: D058665:Adrenergic beta-1 Receptor Agonists; D019390:Arrestins; D002395:Catecholamines; D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; C082333:arrestin3; D019205:GTP-Binding Protein alpha Subunits, Gs; D007545:Isoproterenol; D004837:Epinephrine
keywords: G protein; G protein-coupled receptor (GPCR); adrenergic receptor; arrestin; fluorescence resonance energy transfer (FRET); kinetics; voltage-dependence