Characterization of volume-sensitive, calcium-permeating pathways in the osteosarcoma cell line UMR-106-01.
Characterization of volume-sensitive, calcium-permeating pathways in the osteosarcoma cell line UMR-106-01.
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DOI：
10.1016/s0021-9258(18)83753-x
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发表时间：
1989-03
期刊：
影响因子：
--
通讯作者：
D. Yamaguchi;J. Green;C. Kleeman;S. Muallem
中科院分区：
文献类型：
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作者：
D. Yamaguchi;J. Green;C. Kleeman;S. Muallem
采用Fura 2测定细胞体积变化、胞浆游离Ca ~（2+）浓度[（Ca ~（2+）]i]和碘化3，3 ′-二丙基硫代二碳菁测定细胞膜电位的方法，研究了成骨细胞骨肉瘤细胞系UMR-106-01细胞体积变化对Ca ~（2+）内流和细胞膜电位的影响。肿胀的细胞由低渗透压应力，其次是细胞体积的减少，这是显着受损的介质Ca 2+的去除。因此，细胞肿胀导致[Ca ~（2+）] i增加仅在培养基Ca ~（2+）存在下。细胞肿胀激活的Ca 2+进入途径在静息膜电位下是活跃的，并且通过该途径的Ca 2+内流在细胞超极化时显著增加。Ca ~（2+）内流与跨膜电位呈线性关系。因此，UMR-106-01细胞中体积激活的Ca 2+渗透途径具有导电特性。当不允许细胞进行容量调节时，这些通路不会随时间自发地改变。微摩尔浓度的尼卡地平和La 3+可阻断该途径，但对地尔硫卓和维拉帕米的敏感性极低。体积敏感的Ca 2+渗透途径的激活不依赖于[Ca 2 +]i的增加。同样地，该通路的激活与膜电位在−85和−3 mV之间的变化无关。[Ca ~（2+）] i增加导致细胞超极化，可能是由于Ca ~（2+）激活的K ~+通道激活所致。等渗条件下的体积敏感的途径是部分活跃的。它们的活性受到细胞收缩的抑制，并增加细胞肿胀。这些途径对细胞体积的微小变化敏感，特别是在310 mosM的中等渗透压浓度附近。
Measurements of cell volume changes, free cytosolic Ca2+concentration [(Ca2+]i) with Fura 2 and cell membrane potential with 3,3‵-dipropylthiodicarbocyanine iodide were used to study the effect of cell volume change on Ca2+influx and the membrane potential of the osteoblastic osteosarcoma cell line, UMR-106-01. Swelling the cells by hypo-osmotic stress was followed by reduction in cell volume which was markedly impaired by removal of medium Ca2+. Accordingly, cell swelling resulted in [Ca2+]iincrease only in the presence of medium Ca2+. The cell swelling-activated Ca2+entry pathway was active at resting membrane potentials, and Ca2+influx through this pathway markedly increased upon cell hyperpolarization. A linear relationship between Ca2+entry and the potential across the plasma membrane was observed. Thus, the volume-activated Ca2+permeating pathway in UMR-106-01 cells has conductive properties. These pathways do not spontaneously inactivate with time when the cells are not allowed to volume regulate. The pathway can be blocked by micromolar concentrations of nicardipine and La3+but display very low sensitivity to diltiazem and verapamil. Activation of the volume-sensitive, Ca2+permeating pathway was not dependent on an increase in [Ca2+]i. Likewise, activation of the pathway was independent of a change in membrane potential between −85 and −3 mV. The increase in [Ca2+]iresulted in hyperpolarization of the cells, probably due to activation of Ca2+-activated K+channels. The volume-sensitive pathways were partially active under isotonic conditions. Their activity was inhibited by cell shrinkage and increased by cell swelling. The pathways were sensitive to small changes in cell volume, particularly around a medium osmolarity of 310 mosM.