ヒガイ　コウジ   Higai Koji   檜貝　孝慈    所属   東邦大学  薬学部 薬学科    職種   教授
論文種別	原著
言語種別	英語
査読の有無	査読あり
表題	Noradrenaline-induced relaxation of urinary bladder smooth muscle is primarily triggered through the β₃-adrenoceptor in rats
掲載誌名	正式名：Biological & Pharmaceutical Bulletin 略　 称：BPB ISSNコード：09186158
掲載区分	国内
出版社	Bulletins of the Pharmaceutical Society of Japan
巻・号・頁	42(5),pp.736-743
著者・共著者	Obara K†, Suzuki S†, Shibata H†, Yoneyama N†, Hamamatsu S†, Yamaki F†, Higai K†, Tanaka Y＊†
発行年月	2019/05
概要	β-Adrenoceptors are subclassified into three subtypes (β1–β3). Among these, β3-adrenoceptors are present in various types of smooth muscle and are believed to play a role in relaxation responses of these muscles. β3-Adrenoceptors are also present in urinary bladder smooth muscle (UBSM), although their expression varies depending on the animal species. To date, there has been little information available about the endogenous ligand that stimulates β3-adrenoceptors to produce relaxation responses in UBSM. In this study, to determine whether noradrenaline is a ligand of UBSM β3-adrenoceptors, noradrenaline-induced relaxation was analyzed pharmacologically using rat UBSM. We also assessed whether noradrenaline metabolites were ligands in UBSM. In isolated rat urinary bladder tissues, mRNAs for β1-, β2-, and β3-adrenoceptors were detected using reverse transcription polymerase chain reaction. In UBSM preparations contracted with methacholine (3 × 10−5 M), noradrenaline-induced relaxation was not inhibited by the following antagonists: atenolol (10−6 M; selective β1-adrenoceptor antagonist), ICI-118,551 (3 × 10−8 M; selective β2-adrenoceptor antagonist), propranolol (10−7 M; non-selective β-adrenoceptor antagonist), and bupranolol (10−7 M; non-selective β-adrenoceptor antagonist). In the presence of propranolol (10−6 M), noradrenaline-induced relaxation was competitively inhibited by bupranolol (3 × 10−7–3 × 10−6 M) or SR59230A (10−7–10−6 M; selective β3-adrenoceptor antagonist), with their pA2 values calculated to be 6.64 and 7.27, respectively. None of the six noradrenaline metabolites produced significant relaxation of methacholine-contracted UBSM. These findings suggest that noradrenaline, but not its metabolites, is a ligand for β3-adrenoceptors to produce relaxation responses of UBSM in rats.