EXTRACELLULAR ATP INDUCES A LARGE NONSELECTIVE CONDUCTANCE IN MACROPHAGE PLASMA-MEMBRANES
EXTRACELLULAR ATP INDUCES A LARGE NONSELECTIVE CONDUCTANCE IN MACROPHAGE PLASMA-MEMBRANES
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DOI：
10.1073/pnas.85.21.7988
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发表时间：
1988-11-01
影响因子：
11.1
通讯作者：
LEIJH, PCJ
中科院分区：
文献类型：
--
作者：
BUISMAN, HP;STEINBERG, TH;LEIJH, PCJ
细胞外ATP在其四阴离子形式（ATP 4-）诱导离子通量和膜去极化的小鼠巨噬细胞样细胞系J774.2和居民小鼠巨噬细胞。我们用膜片钳和细胞内微电极技术分析了细胞外ATP 4-的作用。J774.2细胞的全细胞膜片配置膜电位测量显示，ATP 4-诱导的去极化发生在40毫秒内的脉冲应用ATP，是完全可逆的。去极化伴随着膜电导的急剧增加，并且在30分钟的时间内没有显示出适应ATP的迹象。在5 mM总ATP（ATPt）下，全细胞电导为10 nS，和20 pS的单通道电导的上限已经建立。在跨膜的不对称K+、N+、Ca 2+和Cl-浓度下，与ATP诱导的去极化相关的反转电位为0 mV。在膜片钳细胞中，去极化在20 μ M ATP 4-下完成，从完全去极化的复极化在约5秒内发生。相反，在通过微电极穿刺测量的完整细胞中，完全去极化发生在约2mM ATP 4-，而复极化慢得多（约2mM ATP 4-）。100分钟）。这些发现表明ATP处理后细胞内离子组成的变化影响细胞复极化的速率。在较低浓度的ATP，钾电导调制ATP的去极化作用。ATP也使小鼠腹腔巨噬细胞去极化，但通过长期暴露于ATP而衍生自J774.2细胞的变异细胞系（ATPR B2）对ATP不敏感。我们的结果提供了对细胞外ATP诱导的巨噬细胞大的非选择性质膜电导的膜电生理描述和分析。
Extracellular ATP in its tetra-anionic form (ATP4-) induces ion fluxes and membrane depolarization in the mouse macrophage-like cell line J774.2 and in resident mouse macrophages. We analyzed the effects of extracellular ATP4- by both patch-clamp and intracellular microelectrode techniques. Whole-cell patch-configuration membrane potential measurements on J774.2 cells revealed that ATP4--induced depolarization occurred within 40 ms of pulsed application of ATP and was completely reversible. The depolarizations were accompanied by a dramatic increase in membrane conductance and showed no sign of adaptation to ATP over a period of 30 min. At 5 mM total ATP (ATPt) the whole-cell conductance was .apprxeq. 10 nS, and an upper limit of 20 pS for a single-channel conductance has been established. The reversal potential associated with the ATP-induced depolarization at asymmetric K+, N+, Ca2+, and Cl- concentrations across the membrane was 0 mV. In patch-clamped cells depolarization was complete at 20 .mu.M ATP4-, and repolarization from full depolarization occurred in .apprxeq.5 s. In contrast, in intact cells measured by microelectrode impalement, complete depolarization occurred at .apprxeq.2 mM ATP4- and repolarization was much slower (.apprxeq. 100 min). These findings indicate that the changes in intracellular ionic composition that occur after ATP treatment affect the rate of cell repolarization. At lower concentrations of ATP, potassium conductances modulated the depolarizing effect of ATP. ATP also depolarized mouse peritoneal macrophages, but a variant cell line (ATPR B2), derived from J774.2 cells by prolonged exposure to ATP, was insensitive to ATP. Our results provide a membrane electrophysiological description and analysis of a large nonselective plasma membrane conductance of macrophages induced by extracellular ATP.