Intracellular pH regulation in the renal proximal tubule of the salamander. Basolateral HCO3- transport.
Intracellular pH regulation in the renal proximal tubule of the salamander. Basolateral HCO3- transport.
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DOI：
10.1085/jgp.81.1.53
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发表时间：
1983-01
期刊：
影响因子：
--
通讯作者：
Boulpaep EL
中科院分区：
文献类型：
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作者：
Boron WF;Boulpaep EL
我们使用pH、Na和cl敏感微电极研究了虎蝾螈（Ambystoma tigrinum）离体近端灌注小管中的基底外侧HCO3-运输。在一系列实验中，我们在恒定的co2分压下，通过将[HCO3-]b从10 mM减少到2 mM，将基侧pH （pHb）从7.5降低到6.8。pHb和[HCO3-]b的减少导致pHi的大幅（约0.35）快速下降以及基底外侧膜的瞬时去极化。将pHb和[HCO3-]b恢复正常会产生相反的效果。类似的管腔pH （pHl）和[HCO3-]l的降低只有轻微的影响。[HCO3-]b和pHb的减少也会导致aiNa的可逆下降。在第二个系列实验中，我们在恒定的[HCO3-]b和ph下还原了[Na+]b，也观察到pHi的快速下降和短暂的基底侧去极化。通过使[Na+]b恢复正常，这些变化被逆转。在HCO3-存在的情况下改变[Na+]l或在名义上不存在HCO3-的情况下改变[Na+]b的效果要小得多。虽然改变[HCO3-]b或[Na+]b对pHi和基底侧膜电位的影响在很大程度上被4-乙酰氨基-4-异硫氰二苯乙烯-2,2'-二磺酸盐（SITS）阻断，但它们不受Cl-去除的影响，也没有伴随的aiCl的变化，这与Cl-通量与Na+和HCO3-通量之间的紧密联系一致。上述变化显然是由单一输运系统介导的，不涉及Cl-。我们得出结论，HCO3-转运仅限于基底外侧膜，而HCO3-通量与Na+的通量有关。数据与电致Na/HCO3转运体兼容，该转运体在同一方向上携带Na+， HCO3-和净负电荷。
We have used pH-, Na-, and Cl-sensitive microelectrodes to study basolateral HCO3- transport in isolated, perfused proximal tubules of the tiger salamander Ambystoma tigrinum. In one series of experiments, we lowered basolateral pH (pHb) from 7.5 to 6.8 by reducing [HCO3-]b from 10 to 2 mM at a constant pCO2. This reduction of pHb and [HCO3-]b causes a large (approximately 0.35), rapid fall in pHi as well as a transient depolarization of the basolateral membrane. Returning pHb and [HCO3-]b to normal has the opposite effects. Similar reductions of luminal pH (pHl) and [HCO3-]l have only minor effects. The reduction of [HCO3-]b and pHb also produces a reversible fall in aiNa. In a second series of experiments, we reduced [Na+]b at constant [HCO3-]b and pHb, and also observed a rapid fall in pHi and a transient basolateral depolarization. These changes are reversed by returning [Na+]b to normal. The effects of altering [Na+]l in the presence of HCO3-, or of altering [Na+]b in the nominal absence of HCO3-, are substantially less. Although the effects on pHi and basolateral membrane potential of altering either [HCO3-]b or [Na+]b are largely blocked by 4-acetamido-4- isothiocyanostilbene-2,2'-disulfonate (SITS), they are not affected by removal of Cl-, nor are there accompanying changes in aiCl consistent with a tight linkage between Cl- fluxes and those of Na+ and HCO3-. The aforementioned changes are apparently mediated by a single transport system, not involving Cl-. We conclude that HCO3- transport is restricted to the basolateral membrane, and that HCO3- fluxes are linked to those of Na+. The data are compatible with an electrogenic Na/HCO3 transporter that carries Na+, HCO3-, and net negative charge in the same direction.