大黄素升高豚鼠结肠带细胞[Ca~(2 )]_i的特征和GDP的抑制作用

利用Fluo -3荧光探针检测细胞内自由Ca2 浓度([Ca2 ]i),研究了大黄素升高豚鼠结肠带细胞[Ca2 ]i 的量—效关系和动态变化特征,及GDP和胞外Ca2 浓度对其的影响。较低浓度大黄素随药物浓度增加使[Ca2 ]i 显著升高 ,更高浓度大黄素有超最大抑制效应。GDP对大黄素升高细胞[Ca2 ]i 的抑制作用随其浓度增加而增强。GDP和胞外Ca2 浓度影响大黄素诱发的[Ca2 ]i 动态变化的结果表明 :GDP使[Ca2 ]i 峰消失 ,胞外无Ca2 导致[Ca2 ]i 随时间显著下降 ,大黄素升高[Ca2 ]i 作用趋向消失。

CHARACTERISTICS OF EMODIN EVOKED i ANDINHIBITION OF GDP IN GUINEA PIG TAENIA COLI CELLS

Intracellular free Ca2 concentration (i) was detected using Fluo-3 fluorescence probe. Relationship between emodin concentration and intracellular i as well as kinetics of i in guinea pig taenia coli cells were studied. In the range of lower emodin concentration,i rose remarkably with increasing of drug concentration. Supermaximal stimulation of emodin inhibited rising of i. Inhibition of GDP on rising of i enhanced with increasing of GDP concentration. Effects of GDP and extracellular Ca2 - free on rising kinetics of emodin evoked i were studied. Peak of i disappeared by adding GDP. When extracellular Ca2 -free, i decreased remarkably with prolonging of time, rising of emodin evoked i tended to disappear. These results suggest that emodin could evoke Ca2 release from intracellular Ca2 pool by activating receptor coupled G protein and promote extracellular Ca2 influx by depolarizing cell membrane potential.