Intracellular alkalinization mobilizes calcium from agonist‐sensitive pools in rat lacrimal acinar cells.
Intracellular alkalinization mobilizes calcium from agonist‐sensitive pools in rat lacrimal acinar cells.
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细胞内碱化可动员大鼠泪腺细胞中激动剂敏感库中的钙。
DOI：
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
A. Elliott
中科院分区：
文献类型：
--
作者：
S. Yodozawa;T. Speake;A. Elliott
1.我们研究了胶原酶分离的大鼠泪腺泡细胞中细胞内pH（pHi）和细胞内游离钙浓度（[Ca 2 +]i）之间的相互作用。荧光染料fura-2和2 '，7'-双（羧乙基）-5-羧基荧光素（BCECF）分别用于测量[Ca 2 +]i和pHi。2.弱碱NH 4Cl的应用使细胞质碱化，并引起[Ca 2 +]i的剂量依赖性增加。三甲胺（TMA）也使胞浆碱化，[Ca ~（2+）]i增加。NH_4Cl或TMA引起的[Ca ~（2+）]i的增加远小于分泌激动剂乙酰胆碱（ACh）引起的[Ca ~（2+）]i的增加。3. NH 4Cl的应用也增加了浸泡在无Ca（2+）培养基中的细胞中的[Ca 2 +]i，表明NH 4Cl从细胞内池释放Ca 2+。4.如果激动剂敏感的细胞内Ca 2+池已被ACh或微粒体Ca（2+）-ATP酶抑制剂2，5-二（叔丁基）氢醌耗尽，则氯化铵对浸泡在无Ca（2+）培养基中的细胞中的[Ca 2 +]i没有影响。在无Ca（2+）的培养基中用NH 4Cl处理细胞减少了ACh释放的Ca 2+的量。这些结果表明，NH_4Cl从ACh释放的同一细胞内池中释放Ca ~（2+）。5.当通过去除弱酸性乙酸盐碱化细胞溶质时，也会触发激动剂敏感池中的钙释放。6.氯化铵导致磷酸肌醇产量适度增加，表明NH 4Cl可能通过增加细胞内1，4，5-三磷酸肌醇浓度释放了储存的Ca 2+。7. NH_4Cl诱发的[Ca ~（2+）]i的增加即使在细胞外Ca ~（2+）存在下也不能持续。相反，当低剂量的ACh被用来引起细胞内Ca 2+释放类似的幅度，持续的Ca 2+内流观察。8.碱化的细胞质似乎部分抑制Ca 2+进入触发毒胡萝卜素或乙酰胆碱。9.我们认为，碱化未受刺激的泪腺泡细胞的细胞质可以从细胞内激动剂敏感的Ca 2+池中释放Ca 2+。然而，通过碱化释放储存的Ca 2+似乎不会触发显著的Ca 2+进入，这可能是因为细胞内碱化抑制了Ca 2+进入途径或将进入途径与储存耗尽耦合的机制。
1. We have investigated interactions between intracellular pH (pHi) and the intracellular free calcium concentration ([Ca2+]i) in collagenase‐isolated rat lacrimal acinar cells. The fluorescent dyes fura‐2 and 2',7'‐bis(carboxyethyl)‐5‐carboxyfluorescein (BCECF) were used to measure [Ca2+]i and pHi, respectively. 2. Application of the weak base NH4Cl alkalinized the cytosol and caused a dose‐dependent increase in [Ca2+]i. Trimethylamine (TMA) also alkalinized the cytosol and increased [Ca2+]i. The increase in [Ca2+]i evoked by NH4Cl or TMA was much smaller than that evoked by the secretory agonist acetylcholine (ACh). 3. Application of NH4Cl also increased [Ca2+]i in cells bathed in Ca(2+)‐free medium, indicating that NH4Cl released Ca2+ from an intracellular pool. 4. Ammonium chloride had no effect on [Ca2+]i in cells bathed in Ca(2+)‐free medium if agonist‐sensitive intracellular Ca2+ pools had been depleted with either ACh or the microsomal Ca(2+)‐ATPase inhibitor 2,5‐di(tert‐butyl)hydroquinone. Treatment of cells with NH4Cl in Ca(2+)‐free medium reduced the amount of Ca2+ released by ACh. These results suggest that NH4Cl released Ca2+ from the same intracellular pool released by ACh. 5. Calcium release from the agonist‐sensitive pool was also triggered when the cytosol was alkalinized by removing the weak acid acetate. 6. Ammonium chloride caused a modest increase in inositol phosphate production, suggesting that NH4Cl may have released stored Ca2+ via an increase in the intracellular inositol 1,4,5‐trisphosphate concentration. 7. The increase in [Ca2+]i evoked by NH4Cl was not sustained even in the presence of extracellular Ca2+. In contrast, when a low dose of ACh was used to evoke intracellular Ca2+ release of similar magnitude, sustained Ca2+ entry was observed. 8. Alkalinizing the cytosol appeared to partially inhibit Ca2+ entry triggered by thapsigargin or by ACh. 9. We suggest that alkalinizing the cytoplasm in unstimulated lacrimal acinar cells can release Ca2+ from the intracellular agonist‐sensitive Ca2+ pool. However, releasing stored Ca2+ via alkalinization does not appear to trigger significant Ca2+ entry, perhaps because intracellular alkalinization inhibits either the Ca2+ entry pathway or the mechanism which couples the entry pathway to store depletion.
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DOI：
10.1073/pnas.89.4.1438
发表时间：
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影响因子：
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DOI：
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发表时间：
1990
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DOI：
10.1152/ajpgi.1992.263.4.g558
发表时间：
1992
期刊：
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影响因子：
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DOI：
10.1152/ajpcell.1992.263.3.c584
发表时间：
1992
期刊：
The American journal of physiology
影响因子：
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作者：
Negulescu,PA;Munck,B;Machen,TE
通讯作者：
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DOI：
10.1016/0005-2736(92)90019-i
发表时间：
1992
期刊：
Biochimica et biophysica acta
影响因子：
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作者：
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通讯作者：
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