多巴胺D1对人鼻息肉上皮细胞中Na +、K +、Cl -协同转运体的刺激作用：多种激素的影响
Dopamine D1 stimulation of Na+,K+,Cl- cotransport in human NPE cells: effects of multiple hormones.
作者信息
Riese K, Beyer A T, Lui G M, Crook R B
机构信息
Cellular Pharmacology Laboratory, Department of Ophthalmology, University of California, San Francisco 94143, USA.
出版信息
Invest Ophthalmol Vis Sci. 1998 Jul;39(8):1444-52.
PURPOSE
To determine the effects of dopamine on Na+,K+,Cl- cotransport in human ciliary nonpigmented epithelial (NPE) cells.
METHODS
The authors used 86Rb+ as a marker for K+ to study ouabain-insensitive, bumetanide-sensitive 86Rb+ uptake in cultured fetal human NPE monolayers.
RESULTS
Na+,K+,Cl- cotransport was stimulated 1.63-fold by 10 microM dopamine. Stimulation was dose dependent, with a maximum stimulation occurring at 10 microM dopamine and an EC50 of 0.5 microM. NaK-ATPase (measured as ouabain-sensitive, bumetanide-insensitive 86Rb+ uptake) and bumetanide-insensitive, ouabain-insensitive 86Rb+ uptake were not affected by dopamine. The D1-receptor-specific antagonist, SCH23390, inhibited stimulation by 10 microM dopamine more than 90% at 1 microM, with an IC50 of 4 nM, whereas the D2-receptor-specific antagonist, sulpiride, was over 250 times less effective. Similarly, a D1 agonist, SKF81297, was more potent than the D2 agonist bromocriptine in stimulation of Na+,K+,Cl- cotransport. The beta-adrenergic antagonists timolol and propranolol did not significantly inhibit stimulation of Na+,K+,Cl- cotransport by dopamine. Conversely, SCH23390, showed minimal inhibition of isoproterenol stimulation of Na+,K+,Cl- cotransport. Stimulation by maximally stimulating concentrations of isoproterenol and dopamine were not additive, but were similar to stimulation by 1 microM forskolin, suggesting that adenylyl cyclase may be close to maximally activated by either catecholamine. In vivo concentrations (stimulation approximately 25% over control) of dopamine, isoproterenol, and norepinephrine added together stimulated Na+,K+,Cl- cotransport 80% to 89% of stimulation by maximal concentrations of these drugs. The protein kinase A inhibitor N-[2-p-bromocinnamylaminoethyl]-5-isoquinolinesulfonamide (H-89) blocked dopamine stimulation of Na+,K+,Cl- cotransport by more than 75%, whereas phorbol 12-myristate 13-acetate (PMA), a protein kinase C activator, given with 10 microM dopamine inhibited Na+,K+,Cl- cotransport by 75% to 80%, similarly to inhibition by PMA given alone.
CONCLUSIONS
Dopamine stimulates Na+,K+,Cl- cotransport in NPE through dopamine-D1-type receptors and activation of protein kinase A. Beta-adrenergic receptors do not appear to play a role. Inhibition of Na+,K+,Cl- cotransport by protein kinase C is dominant over stimulation of Na+,K+,Cl- cotransport through the cyclic adenosine monophosphate pathway.
目的
确定多巴胺对人睫状体非色素上皮（NPE）细胞中Na +、K +、Cl - 协同转运的影响。
方法
作者使用86Rb + 作为K + 的标志物，研究培养的人胎儿NPE单层中哇巴因不敏感、布美他尼敏感的86Rb + 摄取。
结果
10微摩尔多巴胺使Na +、K +、Cl - 协同转运增加1.63倍。刺激呈剂量依赖性，在10微摩尔多巴胺时出现最大刺激，半数有效浓度（EC50）为0.5微摩尔。钠钾ATP酶（以哇巴因敏感、布美他尼不敏感的86Rb + 摄取来衡量）和布美他尼不敏感、哇巴因不敏感的86Rb + 摄取不受多巴胺影响。D1受体特异性拮抗剂SCH23390在1微摩尔时对10微摩尔多巴胺刺激的抑制超过90%，半数抑制浓度（IC50）为4纳摩尔，而D2受体特异性拮抗剂舒必利的效力则低250倍以上。同样，D1激动剂SKF81297在刺激Na +、K +、Cl - 协同转运方面比D2激动剂溴隐亭更有效。β - 肾上腺素能拮抗剂噻吗洛尔和普萘洛尔对多巴胺刺激的Na +、K +、Cl - 协同转运无明显抑制作用。相反，SCH23390对异丙肾上腺素刺激的Na +、K +、Cl - 协同转运的抑制作用最小。最大刺激浓度的异丙肾上腺素和多巴胺的刺激作用不是相加的，而是与1微摩尔福斯高林的刺激作用相似，这表明腺苷酸环化酶可能已被任一儿茶酚胺接近最大程度激活。体内浓度（刺激比对照高约25%）的多巴胺、异丙肾上腺素和去甲肾上腺素共同添加时，刺激的Na +、K +、Cl - 协同转运为这些药物最大浓度刺激的80%至89%。蛋白激酶A抑制剂N - [2 - 对 - 溴肉桂酰胺基乙基] - 5 - 异喹啉磺酰胺（H - 89）使多巴胺对Na +、K +、Cl - 协同转运的刺激作用阻断超过75%，而佛波醇12 - 肉豆蔻酸酯13 - 乙酸酯（PMA），一种蛋白激酶C激活剂，与10微摩尔多巴胺一起使用时抑制Na +、K +、Cl - 协同转运75%至80%，与单独使用PMA的抑制作用相似。
结论
多巴胺通过多巴胺 - D1型受体和蛋白激酶A的激活刺激NPE中的Na +、K +、Cl - 协同转运。β - 肾上腺素能受体似乎不起作用。蛋白激酶C对Na +、K +、Cl - 协同转运的抑制作用强于通过环磷酸腺苷途径对Na +、K +、Cl - 协同转运的刺激作用。
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