Ohashi T, Azuma H
Tokyo Ika Shika Daigaku Iyo Kizai Kenkyusho Hokoku. 1989;23:59-64.
When rat peritoneal mast cells which had been loaded with fluorescent Ca2+ indicator fura-2/AM were exposed to compound 48/80, fura-2 fluorescence was increased in the presence of 1mM extracellular Ca2+, but remained unchanged in the Ca2(+)-eliminated medium. Only in the presence of 1mM extracellular Ca2+, both fura-2 fluorescence and histamine release were increased in response to compound 48/80, depending on the concentration of the stimulant. Both of these responses were attenuated in the same degree by such release inhibitors as disodium cromoglycate and HSR-6071. Fluorescent microscopic observation of fura-2/AM-loaded mast cells revealed that fura-2 fluorescence was densely localized in the granules and the nucleus, but less in the cytoplasm. All these results strongly suggest that increase in the fura-2 fluorescence might not result from the increase in cytoplasmic free Ca2+ concentration, but from binding of fura-2, which had been released together with chemical mediators from granules following stimulation, to extracellular Ca2+. Therefore, it seems likely that the fura-2/AM loading method is inadequate to investigate whether or not the increase in cytoplasmic free Ca2+ concentration triggers release of chemical mediators from mast cells.
当用荧光Ca2+指示剂fura-2/AM负载的大鼠腹膜肥大细胞暴露于化合物48/80时，在存在1mM细胞外Ca2+的情况下，fura-2荧光增加，但在Ca2+去除的培养基中保持不变。仅在存在1mM细胞外Ca2+的情况下，fura-2荧光和组胺释放均因化合物48/80而增加，这取决于刺激剂的浓度。这些反应均被色甘酸二钠和HSR-6071等释放抑制剂以相同程度减弱。对负载fura-2/AM的肥大细胞进行荧光显微镜观察发现，fura-2荧光密集地定位于颗粒和细胞核中，而在细胞质中较少。所有这些结果强烈表明，fura-2荧光的增加可能不是由于细胞质游离Ca2+浓度的增加，而是由于刺激后从颗粒中与化学介质一起释放的fura-2与细胞外Ca2+结合所致。因此，fura-2/AM负载方法似乎不足以研究细胞质游离Ca2+浓度的增加是否触发肥大细胞释放化学介质。
