title: Differential inhibition by TAK-044 of the inotropic effects of endothelin-1 and endothelin-3.
abstract: The influence of a nonselective antagonist of endothelin receptors, TAK-044 (cyclo-[d-alpha-aspartyl-3-[(4-phenylpiperazin-1-yl)carbonyl]-l-alanyl-l-alpha-aspartyl-d-2-(2-thienyl)glycyl-l-leucyl-d-tryptophyl] disodium), on the positive inotropic effect of endothelin-1 and endothelin-3 was investigated in isolated rabbit myocardium. While TAK-044 produced a concentration-dependent rightward shift of the concentration-response curve for endothelin-1 and endothelin-3, the effect of endothelin-3 was hundred times more sensitive to TAK-044 than that of endothelin-1. The combination of FR139317 ([2-(R)-[2(R)-[2(S)-[[1-(hexahydro-1H-azepinyl)]carbonyl]amino-4-methylpentanoyl]amino-3-[3-(1-methyl-1H-indolyl)]propionyl] amino-3-(2-pyridyl)propionic acid]) and BQ-788 (N-cis-2,6-dimethylpiperidinocarbonyl-l-gamma-methylleucyl-d-1-methoxycarbonyltryptophanyl-d-norleucine) mimicked the inhibitory action of TAK-044 on the positive inotropic effect of endothelin-3 but enhanced the effect of endothelin-1. In a receptor-binding assay, TAK-044 was four times more potent in antagonizing the specific binding of endothelin-1 than that of endothelin-3. Endothelin-1 may activate receptor subtypes that trigger both positive and negative inotropic effects, the latter being more susceptible to the antagonistic action of TAK-044, which may explain in part the differential antagonistic action of TAK-044 on the inotropic effect of endothelin-1 and endothelin-3.
authors.affiliation: Department of Cardiovascular Pharmacology, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata 990-9585, Japan.
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Yomogida
authors.forename: Jun
authors.initials: J
authors.lastname: Maruya
authors.forename: Ikuo
authors.initials: I
authors.lastname: Norota
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Ishii
authors.forename: Masao
authors.initials: M
authors.lastname: Endoh
mesh_terms: D000818:Animals; D001381:Azepines / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1 / Q000037:antagonists & inhibitors* / Q000502:physiology; D019334:Endothelin-3 / Q000037:antagonists & inhibitors* / Q000502:physiology; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D010210:Papillary Muscles / Q000187:drug effects / Q000378:metabolism; D010456:Peptides, Cyclic / Q000008:administration & dosage / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology; D011817:Rabbits; D011869:Radioligand Assay; D044022:Receptor, Endothelin A / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000378:metabolism
chemical_list: D001381:Azepines; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1; D019334:Endothelin-3; D007211:Indoles; D009842:Oligopeptides; D010456:Peptides, Cyclic; D010880:Piperidines; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; C079574:FR 139317; C088196:TAK 044; C086539:BQ 788