Mechanism of basolateral membrane H+/OH-/HCO-3 transport in the rat proximal convoluted tubule. A sodium-coupled electrogenic process.
Mechanism of basolateral membrane H+/OH-/HCO-3 transport in the rat proximal convoluted tubule. A sodium-coupled electrogenic process.
复制标题
基底外侧膜H+/OH-/HCO-3在大鼠近端综合小管中转运的机理。钠耦合的电源过程。
DOI：
10.1085/jgp.86.5.613
复制
发表时间：
1985-11
影响因子：
3.8
通讯作者：
Alpern, R J
中科院分区：
文献类型：
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作者：
Alpern, R J
为了探讨基底外侧膜H+/OH-/HCO-3转运的机制，建立了体内双重微灌注大鼠近曲小管细胞pH值的测量方法。将 pH 敏感荧光素衍生物 (2',7')-双(羧乙基)-(5,6)-羧基荧光素加载到细胞中，并跟踪两个激发波长下荧光的相对变化。使用具有高细胞外钾浓度的尼日利亚菌素完成校准。当管腔和管周液的 pH 值为 7.32 时，细胞 pH 值为 7.14 +/- 0.01。管周 pH 从 7.32 降低至 6.63 导致细胞 pH 从 7.16 +/- 0.02 降低至 6.90 +/- 0.03。这种效应以 2.4 +/- 0.3 pH 单位/分钟的初始速率发生，并被 0.5 mM SITS 抑制。将管周钠浓度从 147 降低至 25 meq/L 导致细胞 pH 从 7.20 +/- 0.03 降低至 6.99 +/- 0.01。管周钠浓度对细胞 pH 值的影响被 0.5 mM SITS 抑制，但不受 1 mM 阿米洛利影响。此外，当在管腔和管周钠完全不存在的情况下管周pH值降低时，细胞酸化速率为0.2+/-0.1pH单位/分钟，比存在钠的情况降低了90%以上。通过增加管周钾浓度实现细胞去极化，导致细胞 pH 值升高，这种效应被管周钡或管腔和管周钠去除所阻断。将管周氯离子浓度从 128 降低至 0 meq/L 不会影响细胞 pH 值。这些结果表明在大鼠近曲小管基底外侧膜上存在生电、钠偶联的 H+/OH-/HCO-3 转运机制。
In order to examine the mechanism of basolateral membrane H+/OH-/HCO-3 transport, a method was developed for the measurement of cell pH in the vivo doubly microperfused rat proximal convoluted tubule. A pH- sensitive fluorescein derivative, (2',7')-bis(carboxyethyl)-(5,6)- carboxyfluorescein, was loaded into cells and relative changes in fluorescence at two excitation wavelengths were followed. Calibration was accomplished using nigericin with high extracellular potassium concentrations. When luminal and peritubular fluids were pH 7.32, cell pH was 7.14 +/- 0.01. Decreasing peritubular pH from 7.32 to 6.63 caused cell pH to decrease from 7.16 +/- 0.02 to 6.90 +/- 0.03. This effect occurred at an initial rate of 2.4 +/- 0.3 pH units/min, and was inhibited by 0.5 mM SITS. Lowering the peritubular sodium concentration from 147 to 25 meq/liter caused cell pH to decrease from 7.20 +/- 0.03 to 6.99 +/- 0.01. The effect of peritubular sodium concentration on cell pH was inhibited by 0.5 mM SITS, but was unaffected by 1 mM amiloride. In addition, when peritubular pH was decreased in the total absence of luminal and peritubular sodium, the rate of cell acidification was 0.2 +/- 0.1 pH units/min, a greater than 90% decrease from that in the presence of sodium. Cell depolarization achieved by increasing the peritubular potassium concentration caused cell pH to increase, an effect that was blocked by peritubular barium or luminal and peritubular sodium removal. Lowering the peritubular chloride concentration from 128 to 0 meq/liter did not affect cell pH. These results suggest the existence of an electrogenic, sodium-coupled H+/OH- /HCO-3 transport mechanism on the basolateral membrane of the rat proximal convoluted tubule.