Carrier-mediated transport of the organic cation procaine amide ethobromide by isolated rat liver parenchymal cells.
Carrier-mediated transport of the organic cation procaine amide ethobromide by isolated rat liver parenchymal cells.
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分离的大鼠肝实质细胞对有机阳离子普鲁卡因酰胺乙溴胺的载体介导的转运。
DOI：
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发表时间：
1978
影响因子：
3.5
通讯作者：
C. Klaassen
中科院分区：
文献类型：
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作者：
D. Eaton;C. Klaassen
用胶原酶灌注法分离肝细胞，研究了普鲁卡因酰胺乙溴化物（PAEB）摄取过程的动力学特征。在30至400微米的底物浓度下测定初始摄取速度（Vo）证明了一个饱和过程，Km为54 +/-10微米，Vmax为0.13 +/-0.01 nmol/min/mg蛋白质。用代谢抑制剂预处理细胞和降低孵育温度显著降低了100微米PAEB的Vo。用锂离子代替钠离子没有效果，而用胆碱代替钠离子使Vo降低了75%。90 min后，PAEB在细胞内的浓度是培养基浓度的18倍，但其中33%以乙酰化形式存在。N4-乙酰PAEB的摄取发生在一个低得多的速率，并达到细胞/培养基的比例只有6 90分钟后。只有一个7季胺测试抑制PAEB摄取在抑制剂/底物比（I/S）为7.5，而五个叔胺显着降低Vo在I/S为0.75，所有五个降低它在7.5的比例。一些有机酸和甾体化合物在I/S为0.75时也显著降低PAEB Vo，而每组的其他化合物在I/S为7.5时没有影响。由于吸收是饱和的，需要代谢能量，并发生对电化学梯度，它表明，PAEB的肝脏积累发生通过一个积极的，载体介导的运输过程。
Using hepatocytes isolated by collagenase perfusion, we studied the kinetic characteristics of the uptake process for procaine amide ethobromide (PAEB). Determination of initial uptake velocities (Vo) at substrate concentrations from 30 to 400 micrometer demonstrated a saturable process with a Km of 54 +/- 10 micrometer and a Vmax of 0.13 +/- 0.01 nmol/min/mg of protein. Pretreatment of cells with metabolic inhibitors and reduction of the incubation temperature significantly reduced the Vo of 100 micrometer PAEB. Replacement of sodium ions with lithium had no effect, while replacement with choline decreased Vo by 75%. The intracellular concentration of PAEB was 18 times the medium concentration after 90 min, but 33% of that was in the acetylated form. Uptake of N4-acetyl PAEB occurred at a much lower rate and reached a cell/medium ratio of only 6 after 90 min. Only one of seven quaternary amines tested inhibited PAEB uptake at an inhibitor/substrate ratio (I/S) of 7.5, while four out of five tertiary amines significantly decreased Vo at an I/S of 0.75 and all five decreased it at a ratio of 7.5. Some organic acids and steroidal compounds also significantly decreased PAEB Vo at an I/S of 0.75, while others from each group had no effect at an I/S of 7.5. Because uptake is saturable, requires metabolic energy, and occurs against an electrochemical gradient, it is suggested that the hepatic accumulation of PAEB occurs via an active, carrier-medicated transport process.