Dawson R, Felheim R, Phillips M I
Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville 32610.
Ren Physiol Biochem. 1994 Mar-Apr;17(2):85-100. doi: 10.1159/000173791.
The ability of a renal epithelial cell line of porcine origin (LLC-PK1) to synthesize dopamine (DA) from L-dopa and release DA into the culture media was studied. L-Dopa was rapidly taken up by LLC-PK1 cells and converted to DA which was then released into the media. L-Dopa uptake and conversion to DA was competitively inhibited by other aromatic amino acids (Tyr and Phe). Studies were conducted to assess L-dopa uptake, DA synthesis and DA release in LLC-PK1 cells in response to changes in the ionic composition of the Krebs-Ringer bicarbonate (KRB) buffer media and to various drugs known to alter renal transport function. Sodium chloride addition to KRB media resulted in enhanced DNA release into the media that was significantly attenuated by both quinine (1 mM) and benzamil (0.1 mM). Other sodium salts (sodium acetate and sodium phosphate) also enhanced DA release from LLC-PK1 cells. Salts containing chloride (LiCl, NH4Cl, choline chloride) stimulated a greater efflux of DA from LLC-PK1 cells than sodium salts at equimolar concentrations. Osmotic stimuli (sucrose, mannitol and dextran, 50-200 mM) also elicited increased DA release from LLC-PK1 cells into the media but not to the same extent as inorganic salts. DA release (secretion) from LLC-PK1 cells was strongly inhibited (25-50%) by drugs known to be substrates for the renal cation transport system. These studies have characterized extensively the factors that govern and regulate the synthesis of DA from L-dopa and the transport system responsible for the secretion (release) of intracellular DA into the media.
研究了猪源肾上皮细胞系（LLC-PK1）从左旋多巴合成多巴胺（DA）并将DA释放到培养基中的能力。左旋多巴被LLC-PK1细胞迅速摄取并转化为DA，然后释放到培养基中。左旋多巴的摄取和向DA的转化受到其他芳香族氨基酸（酪氨酸和苯丙氨酸）的竞争性抑制。进行了多项研究，以评估LLC-PK1细胞中左旋多巴的摄取、DA的合成和DA的释放，以响应克雷布斯-林格碳酸氢盐（KRB）缓冲培养基离子组成的变化以及各种已知会改变肾脏转运功能的药物。向KRB培养基中添加氯化钠会导致DNA释放到培养基中的量增加，而奎宁（1 mM）和苄amil（0.1 mM）均可显著减弱这种增加。其他钠盐（醋酸钠和磷酸钠）也增强了LLC-PK1细胞中DA的释放。在等摩尔浓度下，含氯盐（氯化锂、氯化铵、氯化胆碱）比钠盐刺激LLC-PK1细胞释放更多的DA。渗透刺激（蔗糖、甘露醇和右旋糖酐，50-200 mM）也会使LLC-PK1细胞向培养基中释放的DA增加，但程度不如无机盐。已知作为肾脏阳离子转运系统底物的药物可强烈抑制（25-50%）LLC-PK1细胞中DA的释放（分泌）。这些研究广泛地描述了控制和调节从左旋多巴合成DA的因素以及负责将细胞内DA分泌（释放）到培养基中的转运系统。
