P2 purinoceptors regulate calcium-activated chloride and fluid transport in 31EG4 mammary epithelia
P2 purinoceptors regulate calcium-activated chloride and fluid transport in 31EG4 mammary epithelia
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DOI：
10.1152/ajpcell.00238.2002
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发表时间：
2003-04-01
影响因子：
5.5
通讯作者：
Miller, SS
中科院分区：
文献类型：
--
作者：
Blaug, S;Rymer, J;Miller, SS
据报道，乳腺分泌上皮细胞（MEC）在机械刺激下会释放ATP、UTP和UDP。在此我们研究了ATP/UTP在未转化的克隆小鼠乳腺上皮细胞（31EG4细胞）中引起的生理变化。在对照条件下，跨上皮电位（顶端侧为负）和电阻分别为-4.4±1.3 mV（平均值±标准差，n = 12）和517.7±39.4Ω·cm²。顶端膜电位为-43.9±1.7 mV，顶端与基底外侧膜电阻之比（R - A/R - B）为3.5±0.2。在顶端或基底外侧膜添加ATP或UTP会引起较大的电压和电阻变化，EC₅₀约为24 μM（顶端）和约30 μM（基底）。顶端的ATP/UTP（100 μM）使顶端膜电位去极化17.6±0.8 mV（n = 7），并使R - A/R - B降低约3倍。在任一侧添加腺苷（100 μM）对这些参数均无影响。ATP/UTP的反应被DIDS和苏拉明部分抑制，并由细胞内游离Ca²⁺浓度的瞬时升高介导（427±206 nM；15 - 25 μM ATP，顶端；n = 6）。这种Ca²⁺的升高被环匹阿尼酸、BAPTA或西索菲兰C阻断。31EG4 MEC单层在静息状态下也会分泌或吸收液体，ATP或UTP使液体分泌增加5.6±3 μl·cm⁻²·h⁻¹（n = 10）。药理学实验表明，31EG4上皮细胞在顶端和基底外侧膜上含有P2Y₂嘌呤受体，激活后会刺激顶端Ca²⁺依赖性Cl⁻通道，并导致液体穿过单层分泌。这表明细胞外核苷酸可能在乳腺旁分泌信号传导和体内乳汁成分的调节中起重要作用。
It has been reported that secretory mammary epithelial cells (MEC) release ATP, UTP, and UDP upon mechanical stimulation. Here we examined the physiological changes caused by ATP/UTP in nontransformed, clonal mouse mammary epithelia (31EG4 cells). In control conditions, transepithelial potential (apical side negative) and resistance were -4.4 +/- 1.3 mV (mean +/- SD, n = 12) and 517.7 +/- 39.4 Omega.cm(2), respectively. The apical membrane potential was -43.9 +/- 1.7 mV, and the ratio of apical to basolateral membrane resistance (R-A/R-B) was 3.5 +/- 0.2. Addition of ATP or UTP to the apical or basolateral membranes caused large voltage and resistance changes with an EC50 of similar to24 muM (apical) and similar to30 muM (basal). Apical ATP/UTP (100 muM) depolarized apical membrane potential by 17.6 +/- 0.8 mV (n = 7) and decreased R-A/R-B by a factor of approximate to3. The addition of adenosine to either side (100 muM) had no effect on any of these parameters. The ATP/UTP responses were partially inhibited by DIDS and suramin and mediated by a transient increase in free intracellular Ca2+ concentration (427 +/- 206 nM; 15-25 muMATP, apical; n = 6). This Ca2+ increase was blocked by cyclopiazonic acid, by BAPTA, or by xestospongin C. 31EG4 MEC monolayers also secreted or absorbed fluid in the resting state, and ATP or UTP increased fluid secretion by 5.6 +/- 3 mul.cm(-2).h(-1) (n = 10). Pharmacology experiments indicate that 31EG4 epithelia contain P2Y(2) purinoceptors on the apical and basolateral membranes, which upon activation stimulate apical Ca2+ dependent Cl channels and cause fluid secretion across the monolayer. This suggests that extracellular nucleotides could play a fundamental role in mammary gland paracrine signaling and the regulation of milk composition in vivo.