ヒグチ　ケイ   Higuchi Kei   樋口　慧    所属   東邦大学  薬学部 薬学科    職種   准教授
論文種別	原著
言語種別	英語
査読の有無	査読あり
表題	Proton-coupled organic cation antiporter-mediated uptake of apomorphine enantiomers in human brain capillary endothelial cell line hCMEC/D3.
掲載誌名	正式名：Biological & pharmaceutical bulletin ISSNコード：0918-6158/1347-5215
掲載区分	国内
出版社	PHARMACEUTICAL SOC JAPAN
巻・号・頁	37(2),pp.286-91
著者・共著者	Takashi Okura,Kei Higuchi,Atsushi Kitamura,Yoshiharu Deguchi
担当区分	2nd著者
発行年月	2014/02
概要	R(-)-Apomorphine is a dopamine agonist used for rescue management of motor function impairment associated with levodopa therapy in Parkinson's disease patients. The aim of this study was to examine the role of proton-coupled organic cation antiporter in uptake of R(-)-apomorphine and its S-enantiomer in human brain, using human endothelial cell line hCMEC/D3 as a model. Uptake of R(-)- or S(+)-apomorphine into hCMEC/D3 cells was measured under various conditions to evaluate its time-, concentration-, energy- and ion-dependency. Inhibition by selected organic cations was also examined. Uptakes of both R(-)- and S(+)-apomorphine increased with time. The initial uptake velocities of R(-)- and S(+)-apomorphine were concentration-dependent, with similar Km and Vmax values. The cell-to-medium (C/M) ratio of R(-)-apomorphine was significantly reduced by pretreatment with sodium azide, but was not affected by replacement of extracellular sodium ion with N-methylglucamine or potassium. Intracellular alkalization markedly reduced the uptake, while intracellular acidification increased it, suggesting that the uptake is driven by an oppositely directed proton gradient. The C/M ratio was significantly decreased by amantadine, verapamil, pyrilamine and diphenhydramine (substrates or inhibitors of proton-coupled organic cation antiporter), while tetraethylammonium (substrate of organic cation transporters (OCTs)) and carnitine (substrate of carnitine/organic cation transporter 2; (OCTN2)) had no effect. R(-)-Apomorphine uptake was competitively inhibited by diphenhydramine. Our results indicate that R(-)-apomorphine transport in human blood-brain barrier (BBB) model cells is similar to S(+)-apomorphine uptake. The transport was dependent on an oppositely directed proton gradient, but was sodium- or membrane potential-independent. The transport characteristics were consistent with involvement of the previously reported proton-coupled organic cation antiporter.
DOI	10.1248/bpb.b13-00773
PMID	24257040