CHLORIDE CHANNELS ACTIVATED BY OSMOTIC-STRESS IN T-LYMPHOCYTES
CHLORIDE CHANNELS ACTIVATED BY OSMOTIC-STRESS IN T-LYMPHOCYTES
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DOI：
10.1085/jgp.101.6.801
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发表时间：
1993-06-01
影响因子：
3.8
通讯作者：
CAHALAN, MD
中科院分区：
文献类型：
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作者：
LEWIS, RS;ROSS, PE;CAHALAN, MD
我们使用全细胞和穿孔贴片记录技术来表征 T 和 B 淋巴细胞中体积敏感的 Cl-通道。正跨膜渗透压（细胞内渗透压 > 细胞外渗透压）会触发 Cl- 电导的缓慢诱导。细胞肿胀引起的膜拉伸可能是激活机制的基础，因为施加到移液管内部的适度吸力可以可逆地对抗渗透刺激诱导的 Cl-电流。细胞内 ATP 是维持 Cl- 电流所必需的。使用不含 ATP 的内部溶液，Cl-电流的诱导能力会在全细胞记录的几分钟内下降，而在使用 ATP 的全细胞记录或穿孔贴片实验中，电流可被激活至少 30 分钟。这些通道是阴离子选择性的，渗透性顺序为 I->SCN->NO3-、Br->Cl->MeSO3->乙酸盐、丙酸盐>抗坏血酸盐>天冬氨酸盐和葡萄糖酸盐。 G(Cl) 在 - 100 和 + 100 mV 之间的电势下不表现出电压和时间依赖性的门控行为，但在对称 Cl- 溶液中表现出适度的向外整流。波动分析表明，在对称 160 mM Cl- 存在的情况下，在 - 80 mV 时，单一弦电导约为 2 pS。 Cl-电流渗透激活过程中平均电流与电流方差的关系意味着每个细胞包含大约 10(4) 个可激活的 Cl-通道，使其成为迄今为止描述的淋巴细胞中最丰富的离子通道。 DIDS 和 SITS（在 + 40 mV 下，K(i) 分别 = 17 和 89 muM）以电压依赖性方式阻断电流，阻断程度随着膜去极化而增加。该Cl-通道的生物物理和药理学特性与在低渗条件下触发淋巴细胞体积调节的作用一致。
We have used whole-cell and perforated-patch recording techniques to characterize volume-sensitive Cl- channels in T and B lymphocytes. Positive transmembrane osmotic pressure (intracellular osmolality > extracellular osmolality) triggers the slow induction of a Cl- conductance. Membrane stretch caused by cellular swelling may underlie the activation mechanism, as moderate suction applied to the pipette interior can reversibly oppose the induction of Cl- current by an osmotic stimulus. Intracellular ATP is required for sustaining the Cl- current. With ATP-free internal solutions, the inducibility of Cl- current declines within minutes of whole-cell recording, while in.whole-cell recordings with ATP or in perforated-patch experiments, the current can be activated for at least 30 min. The channels are anion selective with a permeability sequence of I- > SCN- > NO3-, Br- > Cl- > MeSO3- > acetate, propionate > ascorbate > aspartate and gluconate. G(Cl) does not show voltage- and time-dependent gating behavior at potentials between - 100 and + 100 mV, but exhibits moderate outward rectification in symmetrical Cl- solutions. Fluctuation analysis indicates a unitary chord conductance of approximately 2 pS at - 80 mV in the presence of symmetrical 160 mM Cl-. The relationship of mean current to current variance during the osmotic activation of Cl- current implies that each cell contains on the order of 10(4) activatable Cl- channels, making it the most abundant ion channel in lymphocytes yet described. The current is blocked in a voltage-dependent manner by DIDS and SITS (K(i) = 17 and 89 muM, respectively, at + 40 mV), the degree of blockade increasing with membrane depolarization. The biophysical and pharmacological properties of this Cl- channel are consistent with a role in triggering volume regulation in lymphocytes exposed to hyposmotic conditions.