Con A刺激致T淋巴细胞胞浆游离Ca~(2+)浓度升高

本文分别应用荧光Ca~(2+)指示剂Quin2和Indo-1研究了Con A刺激的T淋巴细胞Ca~(2+)]i升高过程及其发生机制.结果表明Con A与T淋巴细胞作用可导致细胞Ca~(2+)]i的迅速升高.这种增加的胞内游离Ca~(2+)不仅来自胞外Ca~(2+)的内流,也来源于胞内钙库的释放.其中Ca~(2+)内流与T细胞钙通道的开放有关.可被钙通道抑制剂戊脉胺抑制,细胞的去极化及钾通道阻断剂四乙胺均不能阻断Ca~(2+)的内流,提示Ca~(2+)内流不是通过电位操纵的钙通道实现的,也与拥通道的开闭无关.Ca~(2+)内流可能是通过Con A受体活化的受体操纵的钙通道而实现的.

INCREASE OF CYTOSOLIC FREE CALCIUM CONCENTRATION OF T LYMPHOCYTES STIMULATED BY CONCANAVALIN A

Fluorescent Ca2+ indicators Quin2 and Indo-1 were employed to investigate the increase of free cytosolic Ca2+ concentration of T lymphocytes stimulated by Con A. It was observed that increase of Ca2 +]i of T lymphocytes occurred within 30 seconds after Con A addition and reached maximum at 2-3 minutes, then slightly declined to a plateau, which showed that the Ca2+]i was about 100nM higher than the resting level. It was also shown that the increase in Ca2+]i induced by Con A stimulation was due to both increased net influx of Ca2+ across the plasma membrane and the release from intracellular calcium stores. The influx is relatively large and is responsible for the sustained plateau,whereas the release of Ca2+ from intracellular calcium stores is small and transient. The increase in Ca2+]i induced by Con A could be blocked by vera-pamil. Neither K+ channel blocker TEA nor depolarization of the membrane by K+-riched PBS could inhibit the Con A-induced increase in Ca2+]i. These results imply that the influx of Ca2+ is membrane potential insensitive and would depend on a kind of Receptor- Operated Ca2+ Channel rather than Potential-Operated Ca2+ Channel. In addition, the Con A-induced increase in Ca2+]i can be enlarged by cytochalasin B.