Redistribution of hepatocyte chloride during L-alanine uptake.
Redistribution of hepatocyte chloride during L-alanine uptake.
复制标题
L-丙氨酸摄取过程中肝细胞氯化物的重新分布。
DOI：
10.1007/bf00211095
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Wondergem,R
中科院分区：
文献类型：
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作者：
Wang,K;Wondergem,R
我们使用离子敏感的双筒微电极来测量肝细胞跨膜电位（Vm），细胞内K+，Cl-和Na+活性（aik，aCliandaNai）和L-丙氨酸摄取过程中的水体积的变化。用对照和实验Krebs生理盐溶液灌注小鼠肝切片。实验溶液含有20 μ ml丙氨酸，对照溶液用蔗糖调节至相同的渗透压（305 mOsm）。肝细胞也加载了50 mm四甲基铵离子（TMA+）10分钟。在细胞内的变化，稳态TMA+活性测定与K+电极的变化，测定在L-丙氨酸摄取过程中细胞水体积的变化。对照组Vm为-33 ± 1 mV，L-丙氨酸摄取使Vm先去极化2±0.2 mV，然后在6 ~ 13 min内使Vm超极化5 mV至-38 ±1 mV（n= 16）。（P< 0.01），而aKi从83±3 mm起无明显变化，而加入哇巴因（1 mm）时，l-丙氨酸仅使Vm增加2 mV，Kid由61±3 mm降至54±5 mm（P< 0.05）。Vmbyl-丙氨酸摄取的超极化也导致faCl从20±2 mm下降到12±3 mm，下降了38%（P< 0.001）。在丙氨酸超极化期间，V和VCl-Vm电压迹线的变化是平行的，这与细胞内Cl−的被动分布与Vmin肝细胞一致。加入Ba ~（2+）可使丙氨酸引起的超极化消失，而aCl则无明显变化。L-丙氨酸摄取过程中肝细胞水体积增加12± 3%。这种膨胀并没有说明l-丙氨酸摄取后离子活性的任何变化。我们的结论是，尽管细胞肿胀和Vm增加，由于增加K+电导，肝细胞Ki是由L-丙氨酸摄取过程中增加的Na+-K+泵活性调节。在l-丙氨酸摄取过程中Vm的超极化提供了电动势以降低aCli。后者可能有助于有机溶质转运过程中肝细胞体积的调节。
We used ion-sensitive, double-barrel microelectrodes to measure changes in hepatocyte transmembrane potential (Vm), intracellular K+, Cl-, and Na+activities (aik,aCliandaNai), and water volume duringl-alanine uptake. Mouse liver slices were superfused with control and experimental Krebs physiological salt solutions. The experimental solution contained 20 μml-alanine, and the control solution was adjusted to the same osmolality (305 mOsm) with added sucrose. Hepatocytes also were loaded with 50 mmtetramethylammonium ion (TMA+) for 10 min. Changes in cell water volume duringl-alanine uptake were determined by changes in intracellular, steady-state TMA+activity measured with the K+electrode. Hepatocyte controlVmwas -33±1 mV.l-alanine uptake first depolarizedVmby 2±0.2 mV and then hyperpolarizedVmby 5 mV to-38±1 mV (n= 16) over 6 to 13 min. During this hyperpolarization,aNaiincreased by 30% from 19±2 to 25±3 mm(P< 0.01), andaKidid not change significantly from 83±3 mm. However, with added ouabain (1 mm)l-alanine caused only a 2-mV increase inVm, but nowaKidecreased from 61±3 to 54±5 mm(P< 0.05). Hyperpolarization ofVmbyl-alanine uptake also resulted in a 38% decrease ofaClifrom 20±2 to 12±3 mm(P< 0.001). Changes inVmandVCl—Vmvoltage traces were parallel during the time ofl-alanine hyperpolarization, which is consistent with passive distribution of intracellular Cl−with theVmin hepatocytes. Added Ba2+abolished thel-alanineinduced hyperpolarization, andaCliremained unchanged. Hepatocyte water volume duringl-alanine uptake increased by 12±3%. This swelling did not account for any changes in ion activities followingl-alanine uptake. We conclude that hepatocyteaKiis regulated by increased Na+-K+pump activity duringl-alanine uptake in spite of cell swelling and increasedVmdue to increased K+conductance. The hyperpolarization ofVmduringl-alanine uptake provides electromotive force to decreaseaCli. The latter may contribute to hepatocyte volume regulation during organic solute transport.