Yasukura T, Inoue M, Irie T, Hara M, Mikami Y, Zeng X T, Mikami T, Omori K, Minato A, Uyama M
Department of Pharmacology, Kansai Medical University, Osaka, Japan.
Jpn J Pharmacol. 1995 Apr;67(4):315-20. doi: 10.1254/jjp.67.315.
Adrenoceptor-mediated Cl- transport in cultured rabbit corneal endothelium was examined using a Cl(-)-sensitive fluorescent dye. The intracellular Cl- concentration ([Cl-]i) in the endothelial cells was estimated to be about 30 mM. Noradrenaline (0.001-0.1 mM) transiently decreased the [Cl-]i in a dose-dependent manner. Such a decrease in [Cl-]i was completely antagonized by pretreatment with the alpha-adrenoceptor antagonist phentolamine (0.1 mM). The selective alpha 2-adrenoceptor agonist UK 14304-18 (5-bromo-6-[(4H,5H-imidazol-2-yl)amino]quinoxaline, 0.1 mM) persistently decreased the [Cl-]i, but neither the alpha 1-adrenoceptor agonist phenylephrine (0.1 mM) nor the beta-adrenoceptor agonist isoproterenol (0.1 mM) had any effect. The alpha 2-adrenoceptor agonist/antagonist yohimbine (0.1 mM) persistently and more strongly decreased the [Cl-]i than UK 14304-18 did. The yohimbine-induced decrease in the [Cl-]i was not further altered by UK 14304-18 or phenylephrine, but partly reversed by noradrenaline, isoproterenol and an adenylate cyclase activator, forskolin (0.1 mM). The yohimbine-induced decrease in [Cl-]i was inhibited by the carbonic anhydrase inhibitor acetazolamide (1 mM), and Cl-/HCO3- exchange inhibitors, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, but not by the H(+)-ATPase inhibitor N,N'-dicylohexylcarbodiimide. The forskolin-induced recovery in [Cl-]i was inhibited by the Na+/K+/Cl- cotransport inhibitor bumetanide (0.1 mM), but not by the Cl- channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoic acid.(ABSTRACT TRUNCATED AT 250 WORDS)
利用一种对Cl⁻敏感的荧光染料，研究了培养的兔角膜内皮细胞中肾上腺素能受体介导的Cl⁻转运。内皮细胞内的Cl⁻浓度（[Cl⁻]i）估计约为30 mM。去甲肾上腺素（0.001 - 0.1 mM）以剂量依赖的方式短暂降低[Cl⁻]i。[Cl⁻]i的这种降低被α-肾上腺素能受体拮抗剂酚妥拉明（0.1 mM）预处理完全拮抗。选择性α₂-肾上腺素能受体激动剂UK 14304 - 18（5-溴-6-[(4H,5H-咪唑-2-基)氨基]喹喔啉，0.1 mM）持续降低[Cl⁻]i，但α₁-肾上腺素能受体激动剂去氧肾上腺素（0.1 mM）和β-肾上腺素能受体激动剂异丙肾上腺素（0.1 mM）均无任何作用。α₂-肾上腺素能受体激动剂/拮抗剂育亨宾（0.1 mM）比UK 14304 - 18更持续、更强烈地降低[Cl⁻]i。育亨宾诱导的[Cl⁻]i降低未被UK 14304 - 18或去氧肾上腺素进一步改变，但被去甲肾上腺素、异丙肾上腺素和腺苷酸环化酶激活剂福斯可林（0.1 mM）部分逆转。育亨宾诱导的[Cl⁻]i降低被碳酸酐酶抑制剂乙酰唑胺（1 mM）以及Cl⁻/HCO₃⁻交换抑制剂4-乙酰氨基-4'-异硫氰基芪-2,2'-二磺酸和4,4'-二异硫氰基芪-2,2'-二磺酸抑制，但未被H⁺-ATP酶抑制剂N,N'-二环己基碳二亚胺抑制。福斯可林诱导的[Cl⁻]i恢复被Na⁺/K⁺/Cl⁻共转运抑制剂布美他尼（0.1 mM）抑制，但未被Cl⁻通道阻滞剂5-硝基-2-(3-苯丙基氨基)-苯甲酸抑制。（摘要截短于250字）
